Appendix C.

SHORT APPROXIMATE METHODS OF SOIL EXAMINATION USED AT THE CALIFORNIA EXPERIMENT STATION.

BY R. H. LOUGHRIDGE.

The California Experiment Station has for many years given the farmers of the State the privilege of having their soils examined to ascertain any physical defects, deficiency in plant-food, or the presence of alkali salts. They have quite generally taken advantage of this, and the number of samples of soil sent in each year has been very large.

A complete analysis of a soil-sample requires fully 15 days; hence the necessity of adopting some quick methods for the determination of the main elements of fertility, viz., humus, lime, potash, and phosphoric acid, that would at the same time give results sufficiently accurate for practical purposes. Similarly for alkali salts in the soil; the leaching-out and analysis of which often occupies more than a week.

The following methods have been adopted, which shorten the time of examination for the plant-food of a soil to about one hour, except for potash, which requires a much longer time. For alkali salts the time is reduced to two days, and less if a pressure filter be used.

Humus.—The Grandeau method of ammonia extraction requires the removal of the lime and magnesia with weak hydrochloric acid, washing out of the acid and then digestion with weak ammonia; all of which, with a soil rich in humus, may require many days, though a number of samples may be put through at the same time.

The method adopted to determine adequacy or inadequacy of the humus (for this is all that is intended in this examination) is completed in less than half an hour. It is based on the color of the humus-extract and avoids the necessity of removal of the lime from the soil.

The soil is pulverized in a mortar with a rubber pestle, and passed through a half-millimeter sieve. Seven grams of the fine earth is placed in a test tube with 15 or 20 cc. of a ten per cent solution of caustic potash and boiled for ten or fifteen seconds, then allowed to settle. The humus is dissolved and the density of the color of the solution is an indication of adequacy or inadequacy. A dense black, non-translucent solution shows the presence of at least one per cent of humus in the soil; a deep brown translucent color indicates about one-half of one per cent; while a light brown color clearly shows a deficiency in the soil, and a need of a good green-manure crop.

Lime.—Two grams of fine earth is treated with a little hydrochloric acid, boiled for a few seconds, and ammonia is added to precipitate the iron and alumina; the whole, with the soil-residue, is quickly thrown on a filter to separate the mass from the lime solution, and washed. After adding ammonium chlorid the lime is precipitated with oxalate of ammonia, and its adequacy for soil-fertility judged of by the turbidity of the solution, or the bulk of the precipitate. Or the latter may be filtered off, dried and weighed. We thus obtain a measure of the carbonate and humate of lime present, by comparing it with the precipitate obtained from a soil whose percentage of lime has been correctly ascertained.

Potash.—The determination of potash in the soils requires more time than either of the other ingredients, and is more rarely made by us. Our knowledge of the soils of the State of California obtained through many analyses, gives us a clue to those localities where potash would probably be deficient, as well as to those whose soils are generally extremely rich in potash; the percentages reaching usually from .5 to as much as 1.5 per cent and more.

For the determination, two grams of the fine earth is digested in hydrochloric acid over a steam bath for two days, the insoluble residue filtered off, the filtrate evaporated to dryness to render the silica insoluble, again filtered and the iron; alumina and lime removed by precipitation with ammonia and oxalate of ammonia and filtration. The filtrate is then evaporated to dryness, the ammonia salts destroyed with aqua regia or driven off by heat, and the alkalies changed to chlorids. Any residue is then filtered off and platin-chlorid added to precipitate the potash, which is separated and determined in the usual way, either by reduction of the platinum by ignition, or by measurement in a Plattner’s potash tube.

Phosphoric Acid.—The determination of phosphoric acid is based on the volume of the phospho-molybdate precipitate in a tube made like a Plattner’s potash tube, but having a wider interior diameter for the smaller portion (not greater than 3 millimeters), and a length of 50 mm. With this diameter, one mm. in height of the precipitate obtained by our short method indicates one one-hundredth of one per cent of phosphoric acid in the soil. The unit of measure must be obtained for each tube, unless of uniform diameter, and is ascertained by taking a soil whose phosphoric-acid percentage has been determined gravimetrically and giving it the following quick treatment; which must, of course, be closely followed in each soil to be examined.

Two grams of the fine earth is ignited in a platinum dish to destroy the organic matter, transferred to a test-tube containing 5 cc. of nitric acid and made to boil for only a couple of seconds, thus preventing the solution of silicates to any material extent. It is not allowed to stand, but a little water is immediately added and it is quickly thrown on a small filter and washed with a little water. The phosphoric acid is then precipitated with molybdic acid at the proper temperature; allowing it to settle, the liquid is drawn off and the precipitate transferred to the measuring-tube. It settles into the small part in a short time if the latter is not too narrow, and is then measured with a millimeter scale. This represents the percentage as found in the soil by the gravimetric method, and serves as a guide for other examinations, whose agreement with gravimetric determinations is generally quite close, and quite sufficient for practical purposes. The rapidity with which the solution is made and separated from the soil is a matter of special importance for comparative results, or determination of percentages; for if the acid solution be allowed to stand for some time before filtration from the soil, silica passes into solution also, and the volume of the molybdate precipitate is increased by it; thus vitiating the results and adding to the time required for the method. By this short method the practically important phosphoric acid in the soil may be approximately determined within half an hour.

SHORT METHOD FOR ALKALI SALTS.

The old method of obtaining solutions of the salts by leaching the soil on a filter until all of the alkali had been washed out has been replaced by the following short one. 50 or 100 grams of the well-mixed soil is placed in a bottle containing 200 cc. of water, shaken up occasionally during 12 hours and allowed to settle. The solution may then be passed through a common filter (or preferably a pressure filter) and an aliquot part (usually 50 cc.) of the filtrate evaporated to dryness in a platinum basin and ignited at a temperature just below redness to destroy any organic matter that may be present. The basin and contents are weighed and the soluble salts are dissolved in a very little water and separated by filtration through a small filter into a 50 cc. cylinder and the alkali carbonates and chlorids determined by titration, being calculated as sodium compounds.

The material remaining on the filter and in the basin, consisting of insoluble earth, carbonates and calcium sulfate, is gently ignited in the basin and weighed; the difference between this and the first weight gives approximately the total soluble salts, which should substantially correspond to the titrations made.

The sulfates are determined by differences between these and the total alkalies. The solution may contain some sulfate of magnesia, or calcium and magnesium chlorids, and these are determined gravimetrically.

Nitrates, which may have been destroyed in the first ignition, are determined in the original solution by the picric method. Any magnesia rendered insoluble by the ignition may usually be accounted for as chlorid, unless much nitrate is present which is rarely the case in carbonated alkali. If much nitric acid was found, it should be first assigned to magnesia.

INDEX.

A. PAGE Absorption and movements of water in soils, 221 of solids from solutions, 267 of gases by soils, 272, 275 Acacias, tolerance of alkali, 480 Accessory minerals, 50 Acid, strength used in soil analysis, 341 Acidic and basic eruptive and metamorphic rocks, 49 Acidity, neutrality, alkalinity of soils, 322 Acids of different strengths, analysis with; table, 326, 341 Action of plants in soil formation, mechanical and chemical, 19 Aeration and reduction as influencing nitrification, 147 effects of insufficient, in soils, 280 excessive, injury in arid regions, 280 Aerobic and anerobic bacteria, 144 Air, functions in soils, 279 “ of soils, composition of, 280 Air-space in soils; figure, 108 Alabama, vegetation and soil-characters, 511 Alaska current, effects on California climate, 296 Alinit, 149 Alkali carbonates and sulfates, inverse ratio, 451, 452 carbonates, effects on clay, 62 effects on culture plants; figure, 426, 427 Alkali-heath, range, tolerance of alkali, figure, 544, 545 Alkali lands, crops for strong, 468 effects of irrigation on, 428 efficacy of shading, 457 exceptionally productive when reclaimed, 483 fertilization not needed in, 483 formation from leachings of slopes, 453 geographical distribution of, 423 high and lasting production when reclaimed, 482 inducements toward reclamation of, 481 in the San Joaquin valley, Cal., figure, 425 possible injury to, from excessive leaching, 462 Alkali lands, summary of conclusions, 453 surface and substrata of, 429 utilization and reclamation of, 455 of world-wide importance, 424 vegetation of, 534 Alkali-resistant crops, 455 Alkali salts, black and white, 441 composition of, 439 composition of; general table, 442, 443 distribution in heavy lands, 436, 437 effects on beet crop, 465 horizontal distribution of, 439 in hill lands, 439 in sandy lands, 433, 435 in Salton Basin, distribution of, 4, 36, 438 leaching-down of, 459 nature of, 423 plant food in, 441, 444 reactions between, 449, 450 reduction by cropping, 463 relative injuriousness of, 464 removal from the soil, 458 removal by deep-furrow irrigation; figure, 460, 461 tolerance of various crop plants; table, 466, 467 total in lands; estimation of, 444 underdrainage the universal remedy for, 460 upward translocation from irrigation, 433 vertical distribution in soils, 429, 431, 432, 434 Alkali soils and seashore lands, 422 calcareous character of, 28 composition of, as a whole, 445, 446, 447 how native plants live in, 430 origin of, 422 repellent aspect, cause of, 424 retention of silica in, 392 Alkali spots, white, 286 Alkali, rise of, 428 turning under of surface, 456 weeds as cattle food, 468 study of, by Loughridge and Davy, 535 Aluminic hydrate, in soils of California and Mississippi; table 101, 390 Alluvial soils, 12 Ammonia-forming bacteria, 149 Ammonia gas, absorption of, by soils; figure, 274, 275 Ammonic carbonate, effects on glass, 18 Ancient civilizations, preference for arid countries, 417 rare in humid countries, 418 Apatite, 63 Arid and humid climates, rock-weathering in, 47 Arid and humid regions, criteria of soils of, 371 contrast between soils of, 28 soils of, 111, 371 Arid and humid soils, general comparison; table, 375, 377 Arid belts, subtropic, 298, 299 utilization of, 299 Arid conditions, local, in tropical countries, 401 Aridity, influence upon civilization, 417 Arid region, bunch grasses on soils of, 111 standing hay in, 300 upland soils of; table, 373, 374 Arid soils, productiveness induces permanent civil organization, 412 Arroyo Grande and Yazoo buckshot soils, 345 Asparagus, resistant to salts, 475 Atmosphere, composition of; table, 16 Azotobacter, 156 Lipman on, 156

B. Bacteria, active in soil-formation, 20 aerobic and anaerobic, 144 denitrifying, 148 food and functions of, 145 in soils, numbers of, 142 micro-organisms of soils, 142 multiplication of, 144 nitrifying, 146 Bacterial life, effect on soil, condition, 149 relation of carbonic dioxid to, 281 Bacteroids, 151 Mork figures, 152, 153 Basaltic rocks, 49 Basalts, red soils from, 52 Basic slag, 64 Basin irrigation, advantages of, 243 Bauxite in soils, 101, 390 Beet, sugar, effects of salts on, 474 tolerant of common salt, 474 Bhil soils, 414 Bicarbonate of soda, 78 Black-alkali lands, difficulty in draining, 462 neutralizing of, 457 waters, use of, 250 why so called, 78 Black earth of Russia, humus in; table, 130 Black sand, 45 Black prairie soils, 53 Black soils and lands, 283 Blizzards in continental America, 298 Blown-out lands, 9 Blue tint in clays and subsoils, 45 Bodengare, 149, 150, 281 Bog ore, formation of, in subsoils, 46, 66 Bones, composition of, 64 Bone meal, efficacy of, 65 Borax, borate of soda, 79 Bottom water, 227 rise of, from irrigation, 227, 230 Bottoms, first and second, contrast between, 506, 507, 509 Bottoms, first, tree growth of, 507, 509 Brahmaputra alluvium, Assam, 413 Brown iron ore, 44 “Buckshot” soils of Yazoo bottom, 116 “Bunch grasses” as alkali-resistants, 471 Burning-out of humus, effects of, 118 Burrowing animals, work in soil-formation, 160

C. Calcareous clay, crumbling on drying, 116 formations, predominance in Europe, 525 soils, definition of, 367, 496, 524 solubility of alumina and silica in, 389 subsoils, and hardpans, 162 Calciphile, calcifuge and silicophile plants, 521 Calcite, calcareous spar, 39 recognition of, 39 Caliche, in Chile, Nevada, and California, 66, 67 Capillarity, 189 Capillary water, reserve of, 229 rise of, 202 to 207 Carbonated water, action on feldspar, 32 action on silicates, 18 universal solvent, 17 Carbonate of soda, 77 injury to soils and plants, 78 Carbonates, chlorids and sulfates of earths and alkalies, reactions between, 449, 450 Carbonic acid, 17 secreted by roots, 20 Carbonic dioxid, absorption of, by soils, 274 heavily absorbed by ferric and aluminic hydrates, 278 occurrence, formation, 17 relation to fungous activity, 281 Cascade range, climatic divide in N. W. America, 297 Caves in limestone regions, 41 Celery, moderate tolerance of alkali, 475 Centrifugal elutriator, Yoder’s, 92 Cereals, alkali-resistance, barley, gluten wheats, 471 Channels, cutting-out by gravel, 6 Charcoal, absorption of gases by, 276, 277 Chemical absorption by soils, 270 action of roots, 20 analysis of soils (in general), 323 character of soil, recognition of, 322 decomposition, causes intensifying, 21 processes of soil formation, 16 Chile saltpeter, 66 Chernozem, 130 analyses of, table, 364 Chestnut, American, a calcifuge tree, 491, 519 Chlorin, largest ingredient of sea water, 27 Chlorite, 36 Chlorosis of vines in marly lands, 526 Churn elutriator, Hilgard’s; figure, 91 Circling of hill lands, 220 Citrus fruits, injury to, from alkali, 478 lemons most sensitive, 478 sensitiveness to common salt, 477 Classification of rocks, 47 of soils, 10 Clay as a soil ingredient, 83 colloidal, 59 functions of, in soils, 59 maintains crumb structure, 110 Clays, claystones, clay shales, 48 colors of, 58 formation, flocculation and deposition of, 33 maturing of, 60 plasticity and adhesiveness, influence of fine powders on, 85 influence of ferric hydrate on, 85 Clay-sandstones, soils from, 57 Clays, separation of, by subsidence, by centrifuge, 89 varieties, enumeration of, and characters, 57, 58 fusibility of, 58 Claystones, soils from, 59 Cleavage of rocks, 3 Cleopatra’s needle, 2 Climate, 287 Climatic and seasonal conditions, 21 Climates, continental, coast and insular, 297 Coffee soils, calcareous, 417 Colloidal clay, amount in soils. Table, 84 analysis of, by Loughridge, 385 effects of alkali carbonates upon, 62 investigation by Schloesing, 59 properties of, 61 separation of, by boiling and kneading, 61 Colloid humates, 133 Colluvial soils, 12 Colors of soils, advantages of, 283 Common salt, injuriousness in soils, 76 recognition of, 76 removal from soils, 76 Conglomerates, 48 Conifers, tall growth of, in arid regions, 517 Contraction of soils in wetting and drying, 114 Co-operation, favored by need of irrigation, 419 Corsican and maritime pine, ash analyses, 520 Cotton, compact growth and heavy boiling on calcareous soils, 503 Cracking of clay soils in drying, 113 Cressa; range, tolerance of alkali, figure, 545, 546 Creep, 12 Crops, alkali-resistant, 455 Crumbling of calcareous clays on drying, 116 Crumb-structure of soils; figure, 110 Crusting of soils, effects of, 111, 117, 221 Cultivated soils, analysis of, 325 investigation of, 316 Cultural experience the final test, 324 Cutting-out of channels by water-borne gravel, 6 Cypress, different forms of; figures, 507, 508

D. Date palm, resistance to alkali, 478 Decomposition, chemical, of rocks, 16 Decolorizing action, of soils, charcoal, 267 Deep-rooting of native plants in arid region, 174 Deforestation, effects of, 219 Deltas, formation of, 7 Denitrifying bacteria, 148 Deserts, effects of winds in, 8 Desert sands, only lack water to become productive, 420 Dew, formation of, 307 rarely adds moisture to soils, 308 within the soil, 308 Differentiation of soil and subsoil, causes of, 121 Distance between furrows and ditches, 241 Dolomite, 42 Drainage, rights-of-way for, 461 Drainage waters, use for irrigation, 250 Drain waters, analyses of, table, 22 leaching effects of, 271 Drouth, resistance to, in arid soils, 167 Dust soils, nature of, 104 slow penetration of water in, 105 Dust storms, 9 Dynamite, used for shattering dense substrata, 181

E. Earth’s crust, known thickness, xxiv Earthworms, action of in soil-formation, 158 Ecological studies, 314 Egypt, obelisks of, 2 Elements constituting earth’s crust, table of, xxiv important to agriculture, list of, xxiv Elutriator, Hilgard’s, figure, 91 Epsomite, epsom salt, in soil, 78 Eremacausis, 129 Erosion in arid regions, 219 in Mississippi table lands; figures, 218 lowering of land by, 15 of rocks by sand; figure, 10 Eruptive rocks, basic and acidic, 49 rocks, soils from, 52 Eucalyptus, tolerance of alkali, 480 European observations on plant distribution, 519 standards of plant-food adequacy—Maercker’s table, 369 Europe, predominance of calcareous formations in, 525 Evaporation and crop yields, calculated, 193 and crop yields, observed (Fortier), 194 and plant growth, 193 counteracting, in alkali lands, 455 dependence on air temperature; Fortier’s experiments, table, 255 from reservoirs and ditches, 257 from water surfaces, 254 wet and moist soils, 254 in different climates, 192, 256 in different localities, California, 255 restrained by loose surface layer, 255 through roots and leaves, amount of, 262, 263 Expansion by oxidation, 18

F. Farmyard or stable manure, 72 Feldspars, weathering of, 31 products of, 32 Ferghana, alkali lands in, 441 Ferric hydrate, effects of, 100 functions of, in soils, 285 high absorptive power of, 277 in Hawaiian soils; table, 356 more diffused in humid than in arid soils, 392 Ferric phosphate, unavailability of, 356 Ferroso-ferric hydrate and oxid, 18, 45 Ferrous oxid, 18 Ferruginous lands, injury from swamping of, 233 Fertilizers, mineral, 63 waste of, by leaching, 269 Flocculation and floccules, 91 Flocculated structure; cements maintaining, 110, 111 Flood-plains of rivers, 14, 15 Fool’s gold, 75 Force exerted by roots, 19 Forecasts, general, of soil quality in forest lands, 507 of soil values, popular, 313 Forest trees, forms of, 499 to 502 of Atlantic states on alkali lands, 481 Form and development of trees, differences in, 498 Forms of leaves, variation in, 502 black-jack oak, 499, 501 post oak, 499, 500 trees, deciduous, in arid region, 516 willow, scarlet, black and Spanish oaks, 502 Freezing water, effects of, 3 Frost, effect of soils, 118 Fruiting, favored by lime in soils, 503 Fungi and molds, action of, 123 functions in humus-formation, 157

G. Gases, absorption of, by soils, 272, 275 partial pressure of, 276 Germination of seeds, 309 Glacier flour, fineness and fertility of, 5 physical analysis of, 5 Glaciers, grinding and abrasion by; figure, 3 Glauber’s salt, 77 Glauconite, in calcareous sandstones, 56 Gneiss soils, 51 Gobi desert, migration of lakes, 9 Going-back of orchards, 182 Grain-sizes, effect on percolation; table, 224 influence on soil texture, 100 Grandeau method of humus estimation, 132 Granite soils, potash and phosphoric acid in, 50 Granitic rocks, weathering of, 47 sand, formation in arid climates, 2 Grano-diorite soils, of Sierra Nevada, 51 Granular sediments, influence upon tilling qualities, 102 Grape-vine, alkali, tolerance of, 475 Grasses, cultivated, sensitive to alkali, 471 Greasewood, range, tolerance of alkali; figure, 542, 543 Greenstones, soils from, 51 Ground water, depth most favorable to crops, 228 variation of surface of, 228 Gulf-stream, 295 Gypsum or selenite, formation from sea-water evaporation, 42 how recognized, 42

H. Halite, 76 Hardpans, causes, formation and cements of, 185 Hardpan, physical, analysis of, 103 plowsole, 241 Hawaiian Islands, humid and arid sides of, 297 soils, analyses of, 356 Hay bacillus; figure, 149, 150 Heat and cold, effects on rocks, 1 of high and low intensity, 304 reflection and dispersion from soil surface, 304 relations to soils and plant growth, 301 trapping of suns, 288 Heaviest clay soils, physical analysis of, 115 Heaving-out of grain, 119 Hematite, 44 Herbaceous plants as soil indicators, 517 Hog-wallows, 114 Hornblende and pyroxene, 33 weathering of, 33 Horsetail rushes, secretion of silica by, 31 Humates and ulmates, 133 cementing effects of, 111 Humid and arid climates, rock-weathering in, 47 Humid region, upland soils of; table, 372, 374 Humification in soils, 20 normal conditions of, 129 tests; Snyder, tables, 140 Humin substances, formation of, 123 Humus, amidic constitution of, 125 and coal, amounts of, from vegetable substance, 128 amount in soils, 133 ash of, from Minnesota soils, analysis, 134 decrease of nitrogen-content with depth, 135 determination in soils, 132 distribution in the surface soil, 157 functions in soils, 21 in arid and humid regions, 138 in black earth of Russia, 130 in Minnesota soils, 131 in North Dakota soils, 133 in the surface soil, 120 losses from cultivation and fallow, 131 nitrogen of, 124, 135 percentage in soils, and nitrogen-content of, tables, 135, 136, 137 porosity of, 124 progressive changes in soils, 126 relation to bacterial content, 144 scanty in arid soils, but rich in nitrogen, 397 substances, physical and chemical nature of, 124 variation of, with original materials, 139 volume weight of, table, 125 versus adipocere, 140 Hydraulic elutriation, 90 Hydromica, 35 Hydrous silicates in soils of arid region, 388

I. Ice-flowers on soils, 119 Immediate plant-food requirements, ascertainment of, 333 productiveness, chemical tests of, 337 productiveness vs. permanent value of soils, 318, 327 India, climatic contrasts, 401 Indian soils, table of analyses, 410 412 types of soils, 411 Indo-Gangetic plain; calcareous hardpan, kankar, 411 Injury from excessive runoff, prevention of, 220 to plants from the various salts, 531 to soils and plants from carbonate of soda, 78 Insects, work in soil-formation, 160 Insoluble residue of soils; less in arid than humid, 384 Insufficient rainfall, leaves sea salts in soils, 28 Insular climate, of Britain, western Europe, 298 Introduction, xxiii Injury from swamping, permanent, 232 Iron carbonate solution, how formed, 44 coloring clays, 58 minerals, 44 pyrite, how recognized, 75 Irrigation, basin, advantages and disadvantages, 244 by check flooding, 237 flooding, 237 furrows, 238 lateral seepage, 242, 241 shallow, deep and wide furrows; diagram, 239 surface sprinkling, 237 underground pipes, 245 ditches, leaky, effects on alkali lands, 429 excessive surface rooting caused by, 245 methods of, 236 necessitates co-operation, 419 Irrigation water, abundant use of saline, 249 duty of, 251 economy in use of, 243 effects of saline, figures, 247 heavy losses in using, 252 limits of salinity, 246, 248 loss by evaporation, 252 loss by percolation; diagram, 253 quality of, 246 saline, how to use, 249 testing penetration of, 242 temperature of, 244 Irrigation, winter, advantages of, 236 Isinglass, 43

J. Janesville loam, chemical analysis of, 331 Japan current, 296 Jasper and hornstone pebbles, weathering of, 30

K. Kainit, composition of, 71 Kaolinite and clay; kaolin, 32 assumes plasticity on trituration with water, 60 crystalline form of, 22, 59 lacks plasticity, 60 Kaolinization, results in zeolite-formation, 395 slow in arid regions, 87, 386

L. Landholding, units of, smaller in arid than in humid region, 420 Landlocked lakes, water of, 27 Land plaster as a fertilizer; effects on soils, 43 Landslides, 12 Laterite soils, Wohltmann’s definition, 416 Terra roxa of Brazil, 416 Leaching of the land, 22 Legumes, bacteria of, 150 mostly sensitive to alkali, 472 Leguminous plants, mostly calciphile; exceptions, 518 Leucite, potash content, 32 Lichens, action on rock-surfaces, 19, 20 Lignites and coal, how formed, 127 Lime a dominant factor in productiveness, 353 Lime carbonate in sea water, 26, 27 removed from earth’s surface, 41 summary of effects in soils, 379 Lime-content, effects of high, in soils, 365 effects on availability of phosophates, table, 366 “Lime-country is a rich country”, 365 Lime, excess of, in arid soils, 378 Lime feldspars, leave lime carbonate in soils, 32 in alkali lands protects plants from salts, 532 lands, failure of tea on, 414 Lime-loving trees, 490 to 492, 497 Lime, most abundantly leached out, 24 percentages, what are adequate, 367 in coast-belt soils, 496, 497 in heavy clay soils; table, 368 Lime renders lower amounts of plant-food adequate, 354 Limestone countries, 53 Rotten, 54 soils, excluded from comparison of arid and humid soils, 376 residual, 53 Limestones, impure, as soil-formers, 40, 53 residual soils of, how formed, 40 soft, or marls, 40 slow disintegration of pure, 63 Limit of acid action on soils, investigation of, by Loughridge, 340 Limonite, 44 Loamy and sandy soils, show little shrinkage, 117 Loose surface layer, illustration of effect, figure, 258, 260 prevention of evaporation by, 257 Loss of humus in summer mulch, 132 Louisiana, vegetation and soil-characters, 512 Lowland tree-growth, 506 Lysimeter, 227

M. Madagascar, character and soils of, 405, 406 climate and rocks of, 406 methods used by Müntz and Rousseaux, 406 potash and lime leached into valleys, 407 red soils, 407, 409 table of soil analyses, 408 Madras, red soils of, 415 Magnesia, effects of excess over lime, 382 exceeds lime in tropical soils, 405 high in arid soils, 381 leached out next to lime, 24 proper proportions to lime, 383 Magnesian limestones as soil-formers, 42 Magnesian soils largely poor, 36 Magnetite, 45 Maize and sorghums, alkali-resistance, 471 Maize roots in humid and arid region, 175, 176 Manganese, more in humid than arid soils, 383 stimulant effects on crops, 383 Marble and limestones, formation of, 39 Marls, gypseous and calcareous, 43 Marly substrata, 186 Marine saline lands, 527 first crops for, 533 reclamation for culture, 534 Matière noire; active nitrification of, 132, 360 Mechanical analysis of soils, 88 Melilots, white and yellow, alkali resistance, 473 Mesas of arid region, 14 Mesopotamia, rehabilitation of, 421 Metamorphic rocks, 46 Methods of irrigation, 236 soil analysis, 325 Mica as a soil ingredient, 35 weathers slowly, 35 mistaken for gold and silver, 35 Mica-schist soils, 51 Micro-organisms of soils, 142 Mineral fertilizers, 63 ingredients of soils, minor, 63 Minerals injurious to agriculture, 73 major soil-forming, and rock-forming, list of, 29 tints of, 18 unessential or injurious to soils, 75 Mirabilite, 77 Mississippi, changes in vegetation from east to west in northern, 490 investigations in, by writer, 489 northern, vegetative belts in; map, 490 vegetative belts, descriptions of, 490, 491, 492 Mississippi river, sediment carried by, 7 Mississippi, southern, central prairie, long-leaf-pine belts, 493 coast-belt; pine meadows; profile, 495 live-oak or shell hammocks, 495 Mississippi valley, climate of, 298 Mississippi water, annual variations in, 25 generalized composition of, 25 Modiola, of Chile, 469 Moisture hygroscopic, table, 196 influence of temperature and air-saturation, 197 method of determining, 197, 198 Mitscherlich’s objections, 199 utility to plant growth, 199 available to growing plants, 211 distribution in soil, as affected by vegetation, 264 evaporated from forests, 265 Eucalyptus, 265 in Russian forests and steppes, 265 requirements of crops in the arid region, 212 Loughridge’s tables of same, 214 supplied by tap roots, 229 useful to crops retained by alkali lands, 433 wasted by weeds, 264 Moraines, in North Central states, 5 Mosses, follow lichens in rock decomposition, 20 Moulds and fungi, action of, 123 Mountain chains, arid climate under lee of, 294 effects of, on rainfall, 293 Muddy waters, 251 Muir glacier, analysis of mud, 5 Mulches, loss of humus, 132 Mulching with straw, sand, 266 Mustard family, sensitive to alkali, 473 Myrobalan root, use for grafting in alkali lands, 479

N. Native vegetation, basis of land values for farmers, 488 causes governing its distribution not an unsolvable problem, 489 result of struggle for existence, 487 Native grasses for alkali lands, 470 Native growth, cogency of conclusions based on, 314 New Mexico, soils from; analysis, 378 Nile water, Letheby’s analyses of, 25 Nitrate deposits, origin of, 67 of soda, 66 Nitrates, waste of, by leaching, 24, 68 Nitrification, active in matière noire, 360 Nitrification and denitrification, 145 in alkali lands, 68 in soil of “ten-acre tract.”, 359 intensity in arid climates, 68 list of substances favoring, 147 of organic matter in soils, experiments, 358 not active in unhumified matter, 359, 360 Nitrifying Bacteria, 146 Nitrobacterium; conditions of activity, 146 Nitrogen-absorbing bacteria, 156 Nitrogen, absorbed more abundantly than oxygen, 278 accumulation of, in humus, 124 adequacy in humus, lowest limit of, 363 in soils, 357 availability of, in soils; ascertainable, 363 content of humus, 135 deficiency, pot test, figure, 362 determination of, in soils, 357 hungry soils; table, 361 percentages in humus, what are adequate, 360 supply of plants, views on, 150 Nitrosomonas, figure, 246 Nodules of legumes, 151 North Central States, herbaceous vegetation on calcareous soils, 514, 515 lowland growth in uplands, when, 515 vegetation and soil-character, 513 Nutritive salts in alkali, 441

O. Ocean currents, Gulf stream and Japan stream, 295, 296 Olive, resistance to alkali, 478 Organic and organized constituents of soils, 120 Organisms influencing soil-conditions, 142 Oxalic acid, secretion by lichens, 19 Oxidation, expansion by, 18 Oxids constituting earth’s crust; table, 31 Oxygen, action in weathering rocks, 18 proportion of, in earth’s crust, 30

P. Pamperos, 9 Peat bogs, 122 Peaty soil, shrinkage, 117 Percolation in natural soils: diagram, 223, 225, 226 rate of, as influenced by grain-sizes, 224 Permanent value of land vs. Immediate productiveness, 340 Physical and chemical causes of vegetative features, 505 conditions of plant growth, 319 Physical analyses, correlation with popular names, 96 results of, 94 table. Mississippi and California soils, 98 analysis of soils, 88 constituents of soils, 10 Physico-chemical investigation of soils, 313 Physiological soil analysis, 333 Phosphate fertilizers, importance of, 65 Phosphate fertilization, in arid region, 393 in California, 393 Phosphoric acid, limits of adequacy in soils, 355 minute amounts leached from soils, 24 no constant difference between arid and humid soils, 393 rendered inert by ferric hydrate, 355 Phosphorites, low-grade, of Nevada, Russia, 63, 64 Plane tree, oriental, resistant to alkali, 480 Plant-adaptation “varying from province to province”, 523 Plant associations, plant formations, 315 Plant distribution, Thurman’s physical theory of, 519 Plant-development under different temperatures, 309 Plant-food, accumulation in finest parts of soils, 87 high percentages mean high land value, 346 ingredients, condition of, in soils, 319 in virgin soils, lowest limit of, table, 352 limits of adequacy, 353 minute amounts may produce large crops, 410 percentages, what are high, 346 percentages, low, 346 water-soluble, reserve, unavailable, 320 Plant-growth on arid subsoils, 166 Plants, deep-rooting in arid region, 174 indicating irreclaimable alkali lands, 535, 536 Plant root action, cannot be imitated in laboratory, 324 Plasticity, absence of, in fine powders, 60 of clay, causes of, 60 lost by burning, 60 Plot tests, difficulties and uncertainties of, 334 plan of, figure, 335 Plowsole, how formed, by shallow irrigation, 186, 241 Poor chalk lands, 525 Pore-space, 108 Porosity of humus, 124 Port Hudson bluff, lignite in, figure, 128 recession of, 116 Potash, abundant in arid soils, 395 and soda in arid and humid region, 394 Potashes, production of detrimental to agriculture, 69 Potash feldspar, supplies potash to soils, 32 fertilization first in humid, last in arid region, 396 from sea water, 69 limits of adequacy in soils, 354 minerals, orthoclase feldspar, 68 preferential retention of, in soils, 272 Salts, Stassfurt, 69 slightly leached out, 24 sulfate, high-grade, 71 Pot-culture tests, 336 Powders, absorption of various gases by, table, 277 Prairie soils, black, 53 Preparation of soils for physical analysis, 89 Productive capacity and duration, forecast of, 346 Progress of humification and formation of coal, table, 126, 127 Pulverulent soils of arid regions, 87 Purifying action of soils, 269 Putrefactive processes, relation to carbonic gas and anaerobic bacteria, 282 Putty soils, 103 Pyroxene, augite, 33, 34

Q. Qualifications required for soil study, 524 Quality of irrigation water, 246 Quince, resistance to alkali, 479 Quartz and allied rocks, 29 sand most prominent ingredient of soils, 30 veins, formation of, 31

R. Rain belts, temperate and tropical, 295 Rainfall, amount of, 215 distribution in California and Montana, 290 in the United States, 215 most important, 290 on the globe, figure, 294 influence on soil formation, 22 insufficient, forms alkali soils, 28 leaves lime behind, 28 natural disposition of, 216 Rains, beating, 221 cold and warm, 302 Reclaimable and irreclaimable alkali lands, 534 Red foothill soils of California, 34 Red or rust-colored soils, 34 advantages of, 284 Regur soils, Deccan, India, 414 formation of, 415 “guvarayi” hardpan, 415 present production, 414 Reh of India, 440 Reserve plant-food in soils, 320 of zeolites, carbonates, phosphates, 321 Residual soils, 11, 13, 22 Rhizobia, adaptation to symbiosis, 154 inoculation of soils with, 154 increase of crops by inoculation with, 155 of legumes, 150 mode of infection, 154 varieties of forms, 154 Rhubarb, sensitive to alkali, 475 Rhyolites, soils from, 53 River bars, formation of, 7 Rivers, amount of dissolved matters carried by, 24 flood-plains of, 13, 14 sediment carried by, 24 waters, analyses of, table, discussion, 23, 24 white and green, 4 Rock crystal, 29 Rocks as soil-formers, 47 chemical decomposition of, 16 cleavage of, 3 definition of, xxiii disintegration of, under extremes of temperature, 2 effects of heat and cold on, 1 erosion of by sand, 10 forming minerals, 29 fragments, rounding of, by flowing water, 6 Rock powder, 85 Rock-weathering in arid and humid climates, 47 Rohhumus, 122 Rolling of soils, of influence of, on heat, 305 Root action, limitation of, 351 Root bacillus, figure, 149, 150 Root crops, effects of alkali upon, 474 Root development in the arid and humid regions, 169 to 176 Rooting, deep, from proper irrigation, 243, 245 Roots, chemical action of, 21 force exerted by, 19 secrete carbonic acid, 20 Root system in the humid region; figure, 168 Rotten Limestone, soils from, analyses, 54 Runoff of rain water, 216 Russia, black earth of; roots and humus in, 130, 363 Rye grass, giant, of Northwest; uses, 470

S. Saline and alkali lands, vegetation of, 527 plants, analyses of ashes of, 530 selective power of, 531 Saline and xerophile vegetation, similarity of, 528 Saline contents of waters, variations of, 250 solutions, structural and functional differences caused by, 528 vegetation, general character of, 527 Saltbushes, Australian, growth and use in California, 469 of Great Basin, probable usefulness, 468 Saltgrass; range, tolerance of alkali, figure, 546, 547 Salton Basin, profile of salts in, 438 Salts, absorption of, by saline plants, 529 Saltwort: range, tolerance of alkali, figure, 540, 542 Samoa and Kamerun soils, analyses by Wohltmann; method, 402 table of, 404 Samphire, Bushy and Dwarf; range, alkali-tolerance, figure, 538, 539, 540 Sand blasts, effects on cobbles, 10 coarse, effect of, on clays, 105 erosion of rocks by; figure, 10 hammocks, of Gulf coast, 56 Sands of arid and humid regions, differences in, 86, 386 table of analyses, 387 Sand, silt and dust, 85 Sandstones, 48 argillaceous, 57 calcareous, formation of, 56 rich soils from, 56 dolomitic, often form poor soils, 56 ferruginous, poor soils from, 56 siliceous, poor soils from, 55 varieties of, 55 zeolitic, soils from, 57 Sandstone soils, lightness of, 55 soils, poor, of humid region, 55 Sand storms, 9 Sandy lands, of arid regions, highly productive, 386 Sandy soils, 30 Schöne’s elutriator, figure, 90 Shrinkage, extent of, in drying soils; figure, 113, 114 Schübler on calcareous soils, 115 Sea water, average composition of, table, 26 chief ingredients useless to plants, 28 minor constituents of, 27 sources of salts in, 26 Sedentary soils, 11, 13, 40 Sedimentary rocks, 47, 48 Sediment deposited by Mississippi in Gulf, 7 Sediments, exhibition of, from physical analysis, 95, 96 number of, in physical analysis, 93 table of diameters and hydraulic values, 94 Seeds, germination of, 309 Semi-humid and semi-arid region, 377, 397 Serpentine, 36 Sieves, use in physical analysis of soils, 88 Silica, absorption and secretion by plants, 31 and alumina, soluble; quantitative relations, 385 solubility in water, 31 soluble, retained in alkali soils, 391 Silicate minerals, 31 Silicates of soda and potash, soluble, 31 Silicon, abundance of, in rocks, xxxi Silicophile plants, a fiction, 522 Sinkholes, 43 Soapstone, 36 Soda in arid and humid regions, 394 Soda, nitrate of, 66 Sodium salts, leached out by drains and rivers, 24 Soil analysis, change of views regarding, 317 discrepant methods used in, 402 practical utility of, 318 Soil and subsoil, causes and processes of differentiation, 120 ill-defined, 120 Soil bacteria, numbers of, 141 Soil character, recognition from native vegetation, 487, 511 Soil-dilution experiments, 347 figures, 348, 349, 350 table of, 350 Soil-examination, short approximate methods for, used at California station, 560 summary directions for, in field or farm, 556 Soil-formation influenced by rainfall, 22 physical processes of, 1 Soil-forming processes accelerated by high temperatures, 398 Soil-grains, number of, 99 surface of, 99 determination by air-flow, 99 by “Benetzungswärme”, 99 investigation, historical review of, 313 moisture, regulation and conservation of, 234 phosphates, solubility in water; Schloesing fils, 332 probe, mode of using, 177 profiles in arid and humid region, 165 Soil, samples, directions for taking, by Calif. Station, 553 sedentary or residual, 11, 13, 40 study, qualifications needed for, 524 surveys, early, of Kentucky, Arkansas and Mississippi, 316 temperature, annual range near surface in arctic and tropical regions, 303 change with depth; table, 303 influence of evaporation on, 307 influence of soil material, 306 influence of surface conditions, 303 influence of vegetation and mulch, 305 tests by crop analysis, Godlewski, Vanderyst, 337, 338 by extraction with organic acids; Dyer, Maxwell, 339 water, different conditions of, 195 Soils, acid-soluble and water-soluble portions most important, 324 alluvial, 12, 13 ancient, in geological formations, xxix calcareous, definition of, 367, 496, 524 classification of, figure, 11 colluvial, 12, 24 definition of, xxix derived from various rocks, 49 effects of crusting on, 221 indefinite action of dilute acids on, 326 interpretation of analyses; Wohltmann, 403 physico-chemical investigation of, 313 (see Table of Contents) Solar radiation, influence of, 302 Solubility, continuous, of soils in water, 328 King’s table, rich and poor soils, 330 Schultze’s table, rich soil, 328 Ulbricht’s table, poor soil, 329 Solvent action of water upon soils, 327 power of water, 17 Solubility, increased with nitrogen-content, 141 Sour grasses, 123 humus, antiseptic properties of, 122 soils, 122 Souring of soils, by cultivation, 123 Stable or farmyard manure, 72 composition of, table, 73 green-manuring only substitute, 74 method of using, in humid region, 74 physical effects of, 73 use of, in the arid region, 74 Stalactites and stalagmites, 41 Stassfurt Salts, discovery of, 69 importance to agriculture, 70 origin of, 70 Stassfurt Salts, nature of, 71 Stonecrops, succeed mosses, 20 Stone fruits, resistance to alkali, 478 Stratified rocks, derived from crystalline, 29 Stunted growth, caused by shallow or very heavy soils, 504 Sturdy growth on calcareous lands, 502, 503 Subsidence method, 89 Subsoils, arid region, 163 and deep plowing, 164 calcareous, 162 rawness of, in humid climates, 163 Substrata in arid region, importance of, 173 faulty, with figures, 177 to 180 impervious, injury from; figure, 181 leachy, 182 marly, 186 Subterranean rivers, 41 Sulfate of potash, high-grade, 71 of soda, dust from, 77 injuriousness to plants, 77 occurrence in arid regions, 77 Sulfates, reduction of, 232 Sulfuric acid in arid and humid regions, 394 Summer mulch, loss of humus in, 132 Sunflower family, resistance to alkali, 473 Sun’s heat, penetration into the soil, 302 Surface crusts, formation of, 111, 117 physical analyses of, 118 Surface, hydrostatic and ground waters, 215 Surface waters, chemical effects of percolation, 161 physical effects of percolation, 161 Swamping of alkali lands, consequences of, 451, 463 irrigated lands, results of, 231 Symbiosis, adaptation to, of Rhizobia, 154 Szek of Hungarian plain, 440

T. Tabashir, 31 Talc and serpentine, 36 Tap-roots, moisture supplied by, 229 Tea, failure on calcareous lands, 414

Temperature, annual mean of, 289 conditions, ascertainment and presentation of, 288 extremes, on high mountains and plateaus, 288 of stellar space, 288 seasonal, monthly and daily means, 289, 291 Temporary vs. permanent productive capacity of soils, 340 Tennessee and Kentucky, vegetation and soil-character, 513 Terraces, river and lake, 14 Testing penetration of irrigation water, 242 Textile plants, tolerance of alkali, 475 Thomas or basic slag, 64 Thurman’s physical theory of plant distribution, 519 Tillage; effects of; figure, 109, 110 how maintained in nature, 111 Titanium in soils, xxxi Time of acid-digestion, different; table, 342 Tolerance of alkali by culture plants, 463 alkali plants; table, 548, 549 Topography, influence of, on climate, 293 Trachytes, 53 Trona, Urao, 77 Tropical soils, 398 are highly leached, 400 often highly colored with iron, 400 do not need early fertilization, 399 humus in; abundant, but low in nitrogen, 399 few determinations made, 399 possible calculation of, 399 investigations of, 401 laterites, not always rich in iron, 400 mostly have low plant-food percentages, 400 resemble the “nimble penny”, 400 Tubercles of legumes, figures, 151, 154 Tufa, calcareous, 41 Tussock grass, food value of, 470 range, alkali-tolerance, figure, 536, 537

U. Ulmin substances, 122 Underdrainage, advantages of, 235 Underdrains, effects of, 234 Unhumified organic matter does not nitrify, 148 Unhumified vegetable matter, utility of, 135, 360 United States, good field for comparative soil study, 524 Upland and lowland growth in arid and humid regions, 515 Usar lands of India, character of, 440 not all alkali lands, 440

V. Vegetative belts, lime a governing factor of, 492 Virgin lands, advantages of soil study in, 318 Virgin soils, analysis by extraction with strong acids, 340 Vivianite, 65 Volatile part of plants, xxxii Volcanic ash, form soils rapidly; soils from, 20, 52 Volcanic glass, 53 Volume of soils, changes on wetting and drying, 122 Volume-weight of soils, 107

W. Walnut, black, a lime-loving tree, 490 to 497 tolerant of white alkali, 479 Washing-away and gullying of land, 217 Water, capillary, 201 ascent in soil columns, figure, 202, 205 uniform sediments, figure, 204, 207 held at different heights in soil column, table, 208 expansion and contraction in absorbing, 208, 209 maximum and minimum of water-holding power, termination of; figure, 202, 207 movements in moist soils, 210 carbonated, solvent power, 17 carrying power, 14 controlling factor of soil temperature, 301 density of, 190 effects of flowing, 5 Water extraction of soils, practical conclusions from, 332 Water, hard, 41 hygroscopic, 196 of lan-locked lakes, 27 loss of, by irrigation in shallow furrows, 240 physical factors of, 188 regulation of temperature by, 191 relations to heat, 189 requirements of growing plants, 192 plants in arid regions, 195 sidewise penetration of, in soils, 241 of soils, chapters on, 188, 215, 234 solvent action upon soils, 327 solvent power, 17, 191 Water-soluble plant-food, 321 specific heat of, 190, 191 table, 227 vaporization of, 191 Watery soil extracts, from European soils; tables, 327, 329 American soils, King, 329, 330 Wave action on shores, figure, 7 Weathering, by oxygen, carbonic acid, water, 16, 17 “ in humid and arid regions, 2, 86 Weight of soils, per acre-foot, 107 White soils, nature of, in humid regions, 285 in arid regions, 286 Wind deposits, 105 Winds, action of, in forming soils, 8 cyclones, and anti-cyclones, 293 effects of, in deserts, 8 heat the cause of, 291 land and sea breeze, 291 trade, and monsoons, 291, 292 Winter irrigation, 236 Wire-basket tests, of Bureau of Soils, 337

X. Xerophile vegetation, similarity to saline, 529

Y. Yazoo bottom, soils of, 116 Yazoo “buckshot” and Arroyo Grande soils, 345

Z. Zeolites, decomposition by acids, 36, 38, 39 exchange of bases in analcite and leucite, 37 formation of, 37 importance in soils, 38 rocks cemented by, 38 Zeolitic sandstones, 57

AUTHORS REFERRED TO.

A. Adametz, L., 142, 281. Agassiz, L., 4. Aso, K., 383.

B. Bamber, —, 401, 410, 414. Batholomew, J. G. 294. Beyerinck, M. W., 151, 156. Blumtritt, E., 276. Bonnier, G., 521. Böttcher, O., 393. Boussingault, J. B., 151, 276, 313. Brick, —, 528. Brock, see Morck, D. Burri, R., 148. Butler, O., 151.

C. Cameron, F. K., 380, 466, 532, 533. Clarke, F. W., XXIV, 23. Colby, G. E., note above. Colmore, C. A., 448. Contejean, Ch., 521, 523, 531. Coville, F. V., 536. Crochetelle, J., 146, 147.

D. Darton, N. H., 10. Darwin, Ch., 158. Davy, J. B., 535. Deherain, P. P., 146, 147. Detmer, W., 127. Djemil, —, 159. Duclaux, P. E., 144. Duggar, J. F., 155. Dumont, J., 146, 147. Dyer, B., 339, 357.

E. Ebermayer, E., 279, 305. Eckart, C. F., 212. Eichorn, —, 327. Ermann, G. A., 303.

F. Fawcett, W., 355. Fischer, Hugo, 156. Fliche, P., 520, 521. Forbes, R. H., 219. Fortier, S., 194, 254. Fraenkel, L., 142. Frank, A., 151. Fuelles, P., 281. Furry, F. E., 73. Furuta, T., 383.

G. Geikie, J., 14. Gerlach, —, 156. Gilbert, G. K., 2. Gilbert, J. H., 151, 192. Godlewski, E., 337, 393 Goss, A., 376, 530. Grandeau, L., 132, 133, 139, 357, 520, 521.

H. Haberlandt, F., 310. Hall, A. D., 210, 227. Hare, R. F., 378. Harper, R. M., 494. Hartwell, B. L., 123. Headden, H. P., 18. Hedin, Sven, 9. Hellriegel, F., 130, 151, 192. Henrici, 200. Hillman, F. H., 536. Hiltner, L., 154. Hoffmann, R., 528. Hohl, J., 143. Hunt, T. S., 23.

J. Jaffa, M. E., 135, 381, 450, 530. Johnson, S. W., 60, 380.

K. Katayama, T., 383. Kearney, T. H., 532. Kedzie, R. C., 343, 375. Kellner, O., 393. King, F. H., 99, 108, 109, 168, 192, 193, 210, 211, 212, 224, 228, 236, 305, 325, 328, 332. Kinsley, J. S., 143. Knop, W., 197. Koch, R., 156, 281. Kossovitch, P., 363. Kosticheff, P., 130, 157. Kröber, 156. Krocker, F., 22. Kuntze, O., 67, 68.

L. Ladd, E. F., 131, 133, 134, 141. Langley, S. P., 288. Lawes, J., 151, 192. Lea, E. C., 387. Leather, J. W., 401, 410, 411, 412, 414 to 417, 440. Lemberg, J., 272 Lesage, M., 528. Letheby, H., 23. Liebig, J. von, 150, 313. Liebscher, G., 354. Lipman, J. G., 156. Loeb, J., 380. Loew, O., 23, 42, 382, 383. Loughridge, R. H., 87, 207, 213, 214, 240, 259, 340 to 342, 385, 430, 462, 466, 513, 535, 560.

M. Maercker, M., 65, 369. Mann, H. H., 401, 410, 413. Manson, M., 294. Maxwell, W., 339. May, D. W., 42, 380. Mayer, A., 199, 207, 209. Mayo, N. S., 143. Mazurenko, D. P., 87. Means, T. H., 248, 478. Merrill, G. P., 2, 13, 167. Middendorff, V., 441. Mitscherlich, E. A., 99, 199. Miquel, P., 142, 281, 359. Mohr, Chas., 489, 511. Moore, G. T., 154. Morck, D., 154. Müller, A., 449. Müller, P. E., 122, 184. Müntz, A., 142, 355, 370, 401, 402, 406 to 410. Murray, John, 23, 24. Myers, H. C., 6, 144.

N. Naegeli, C. v., 129. Nagaoka, M., 65, 393. Nobbe, F., 154.

O. Osterhout, W. J. V., 533. Ototzky, L., 265. Owen, D. D., 316, 317, 343, 513.

P. Peter, A. M., 175. Peter, R., 316,317, 343. Pichard, P., 147. Porter, J. L., 23, 24. Pumpelly, R., 110.

R. Rafter, G. W., 217. Ramann, E. Reade, T. M., 41. Regnault, V., 26. Reichert, E., 276. Richthofen, F. von, 110. Risler, E., 354. Rosenberg, S., 528. Rousseaux, E., 355, 370, 401, 402, 406 to 410. Rudzinski, D., 87. Russell, I. C., 24.

S. Saussure, H. E. de, 150. Schimper, A. F. W., 523, 528. Schloesing, Th., 59, 111, 354. Schloesing, Th., fils, 332, 393. Schmidt, C., 23. Schöne, H. E., 90. Schübler, J. J., 116, 197, 313. Schultze, H., 328, 329. Seton, E. T., 159, 160. Shaler, N. S., 12. Shaw, G. W., 465. Smith, E. A., 511. Snyder, H., 131, 133, 134, 139. Stenhouse, —, 276. Stockbridge, H. E., 307, 308. Stone, C. H. H., 25. Stubenrauch, A. V., 222. Stutzer, A., 149.

T. Thurmann, J., 519, 520. Tolman, L. M., 387. Tourney, J. W., 216. Traphagen, F. W., 23. Tuxen, C. F. A., 184.

U. Udden, J. A., 106. Ulbricht, R., 328.

V. Vanderyst, H., 338. Ville, G., 151. Voelcker, J. A., 22, 410. Vogel, J. H., 156.

W. Wagner, P., 65. Ward, M., 144. Warington, R., 108, 146. Washington, H. S., xxiv. Way, J. T., 22, 73. Weber, A. H., 450. Wheeler, H. J., 123. Whitney, M., 94, 195, 207, 316, 321, 330, 332, 337. Wilfarth, H., 151. Williams, W. E., 60, 100. Winogradsky, S., 146, 156. Wohltmann, F., 355, 370, 401, 402 to 405, 406, 416. Wolff, E., 22, 73. Wollny, E., 110, 113, 125, 147, 159, 195, 264, 279, 281, 284, 305, 306. Wüllner, —, 198. Wunder, G., 327.

Y. Yoder, P. A., 92.

Z. Zöller, P. H., 22.

This writer’s valuable “Boden Runde” (1905) unfortunately came to hand too late to be considered in this volume.

Printed in the United States of America.