Lichens

CHAPTER II. Constituents of the Lichen Thallus

CONSTITUENTS OF THE LICHEN THALLUS

I. LICHEN GONIDIA

1. GONIDIA IN RELATION TO THE THALLUS

A. HISTORICAL ACCOUNT OF LICHEN GONIDIA 21

B. GONIDIA CONTRASTED WITH ALGAE 22

C. CULTURE EXPERIMENTS WITH THE LICHEN THALLUS 24

D. THEORIES AS TO THE ORIGIN OF GONIDIA 25

E. MICROGONIDIA 26

F. COMPOSITE NATURE OF THALLUS 27

G. SYNTHETIC CULTURES 27

H. HYMENIAL GONIDIA 30

I. NATURE OF ASSOCIATION BETWEEN ALGA AND FUNGUS 31 a. Consortium and symbiosis b. Different forms of association

J. RECENT VIEWS ON SYMBIOSIS AND PARASITISM 36

2. PHYSIOLOGY OF THE SYMBIONTS

A. NUTRITION OF LICHEN ALGAE 39 a. Character of algal cells b. Supply of nitrogen c. Effect on the alga d. Supply of carbon e. Nutrition within the symbiotic plant f. Affinities of lichen gonidia

B. NUTRITION OF LICHEN FUNGI 44

C. SYMBIOSIS OF OTHER PLANTS 45

II. LICHEN HYPHAE

A. ORIGIN OF HYPHAE 46

B. DEVELOPMENT OF LICHENOID HYPHAE 47

C. CULTURE OF HYPHAE WITHOUT GONIDIA 49

D. CONTINUITY OF PROTOPLASM IN HYPHAL CELLS 51

III. LICHEN ALGAE

A. TYPES OF ALGAE 51 a. Myxophyceae associated with Phycolichens b. Chlorophyceae associated with Archilichens

B. CHANGES INDUCED IN THE ALGA 60 a. Myxophyceae b. Chlorophyceae

C. CONSTANCY OF ALGAL CONSTITUENTS 63

D. DISPLACEMENT OF ALGAE WITHIN THE THALLUS 64 a. Normal displacement b. Local displacement

E. NON-GONIDIAL ORGANISMS ASSOCIATED WITH LICHEN HYPHAE 65

F. PARASITISM OF ALGAE ON LICHENS 65

CHAPTER III. Morphology

MORPHOLOGY

I. GENERAL ACCOUNT OF LICHEN STRUCTURE

ORIGIN OF LICHEN STRUCTURES

A. FORMS OF CELL-STRUCTURE 67

B. TYPES OF THALLUS 68 a. Endogenous thallus b. Exogenous thallus

II. STRATOSE THALLUS

1. CRUSTACEOUS LICHENS

A. GENERAL STRUCTURE 70

B. SAXICOLOUS LICHENS 70 a. Epilithic lichens aa. Hypothallus or protothallus bb. Formation of crustaceous tissues cc. Formation of areolae b. Endolithic lichens c. Chemical nature of the substratum

C. CORTICOLOUS LICHENS 77 a. Epiphloeodal lichens b. Hypophloeodal lichens

2. SQUAMULOSE LICHENS

A. DEVELOPMENT OF THE SQUAMULE 79

B. TISSUES OF SQUAMULOSE THALLUS 81

3. FOLIOSE LICHENS

A. DEVELOPMENT OF FOLIOSE THALLUS 82

B. CORTICAL TISSUES 82 a. Types of cortical structure b. Origin of variation in cortical structure c. Loss and renewal of cortex d. Cortical hairs

C. GONIDIAL TISSUES 87

D. MEDULLA AND LOWER CORTEX 88 a. Medulla b. Lower cortex c. Hypothallic structures

E. STRUCTURES FOR PROTECTION AND ATTACHMENT 91 a. Cilia b. Rhizinae c. Haptera

F. STRENGTHENING TISSUES OF STRATOSE LICHENS 95 a. Produced by development of cortex b. Produced by development of veins or nerves

III. RADIATE THALLUS

1. CHARACTERS OF RADIATE THALLUS

2. INTERMEDIATE TYPES OF THALLUS

3. FRUTICOSE AND FILAMENTOUS THALLUS

A. GENERAL STRUCTURE OF THALLUS 101

Cortical Structures a. The fastigiate cortex b. The fibrous cortex

B. SPECIAL STRENGTHENING STRUCTURES 103 a. Sclerotic strands b. Chondroid axis

C. SURVEY OF MECHANICAL TISSUES 105

D. RETICULATE FRONDS 106

E. ROOTING BASE IN FRUTICOSE LICHENS 108

IV. STRATOSE-RADIATE THALLUS

1. STRATOSE OR PRIMARY THALLUS

A. GENERAL CHARACTERISTICS 111

B. TISSUES OF PRIMARY THALLUS 112 a. Cortical tissue b. Gonidial tissue c. Medullary tissue d. Soredia

2. RADIATE OR SECONDARY THALLUS

A. ORIGIN OF THE PODETIUM 114

B. STRUCTURE OF THE PODETIUM 114 a. General structure b. Gonidial tissue c. Cortical tissue d. Soredia

C. DEVELOPMENT OF THE SCYPHUS 117 a. From abortive apothecia b. From polytomous branching c. From arrested growth d. Gonidia of the scyphus e. Species without scyphi

D. BRANCHING OF THE PODETIUM 119

E. PERFORATIONS AND RETICULATION OF THE PODETIUM 120

F. ROOTING STRUCTURES OF CLADONIAE 121

G. HAPTERA 122

H. MORPHOLOGY OF THE PODETIUM 122

I. PILOPHORUS AND STEREOCAULON 125

V. STRUCTURES PECULIAR TO LICHENS

1. AERATION STRUCTURES

A. CYPHELLAE AND PSEUDOCYPHELLAE 126 a. Historical b. Development of cyphellae c. Pseudocyphellae d. Occurrence and distribution

B. BREATHING-PORES 129 a. Definite breathing-pores b. Other openings in the thallus

C. GENERAL AERATION OF THE THALLUS 132

2. CEPHALODIA

A. HISTORICAL AND DESCRIPTIVE 133

B. CLASSIFICATION 135 I. CEPHALODIA VERA II. PSEUDOCEPHALODIA

C. ALGAE THAT FORM CEPHALODIA 136

D. DEVELOPMENT OF CEPHALODIA 137 a. Ectotrophic b. Endotrophic c. Pseudocephalodia

E. AUTOSYMBIOTIC CEPHALODIA 140

3. SOREDIA

A. STRUCTURE AND ORIGIN OF SOREDIA 141 a. Scattered soredia b. Isidial soredia c. Soredia as buds

B. SORALIA 144 a. Form and occurrence of soralia b. Position of soraliferous lobes c. Deep-seated soralia

C. DISPERSAL AND GERMINATION OF SOREDIA 147

D. EVOLUTION OF SOREDIA 148

4. ISIDIA

A. FORM AND STRUCTURE OF ISIDIA 149

B. ORIGIN AND FUNCTION OF ISIDIA 151

VI. HYMENOLICHENS

A. AFFINITY WITH OTHER PLANTS 152

B. STRUCTURE OF THALLUS 153

C. SPORIFEROUS TISSUES 154

CHAPTER IV. Reproduction

REPRODUCTION

I. REPRODUCTION BY ASCOSPORES

A. HISTORICAL SURVEY 155

B. FORMS OF REPRODUCTIVE ORGANS 156 a. Apothecia b. Perithecia

C. DEVELOPMENT OF REPRODUCTIVE ORGANS 159

1. DISCOLICHENS

a. Carpogonia of gelatinous lichens b. Carpogonia of non-gelatinous lichens c. General summary d. Hypothecium and paraphyses e. Variations in apothecial development aa. Parmeliae bb. Pertusariae cc. Graphideae dd. Cladoniae

2. PYRENOLICHENS

a. Development of the perithecium b. Formation of carpogonia

D. APOGAMOUS REPRODUCTION 174

E. DISCUSSION OF LICHEN REPRODUCTION 177 a. The Trichogyne b. The Ascogonium

F. FINAL STAGES OF APOTHECIAL DEVELOPMENT 181 a. Open or closed apothecia b. Emergence of ascocarp

G. LICHEN ASCI AND SPORES 184 a. Historical b. Development of the ascus c. Development of the spores d. Spore germination e. Multinucleate spores f. Polaribilocular spores

II. SECONDARY SPORES

A. REPRODUCTION BY OIDIA 189

B. REPRODUCTION BY CONIDIA 190 a. Rare instances of conidial formation b. Comparison with Hyphomycetes

C. CAMPYLIDIUM AND ORTHIDIUM 191

III. SPERMOGONIA OR PYCNIDIA

A. HISTORICAL ACCOUNT OF SPERMOGONIA 192

B. SPERMOGONIA AS MALE ORGANS 193

C. OCCURRENCE AND DISTRIBUTION 193 a. Relation to thallus and apothecia b. Form and size c. Colour

D. STRUCTURE 196 a. Origin and growth b. Form and types of spermatiophores c. Periphyses and sterile filaments

E. SPERMATIA OR PYCNIDIOSPORES 201 a. Origin and form b. Size and structure c. Germination d. Variation in pycnidia

F. PYCNIDIA WITH MACROSPORES 204

G. GENERAL SURVEY 205 a. Sexual or asexual b. Comparison with fungi c. Influence of symbiosis d. Value in diagnosis

CHAPTER V. Physiology

PHYSIOLOGY

I. CELLS AND CELL PRODUCTS

A. CELL-MEMBRANES 209 a. Chitin b. Lichenin and allied carbohydrates c. Cellulose

B. CONTENTS AND PRODUCTS OF THE FUNGAL CELLS 213 a. Cell-substances b. Calcium Oxalate c. Importance of calcium oxalate

C. OIL-CELLS 215 a. Oil-cells of endolithic lichens b. Oil-cells of epilithic lichens c. Significance of oil-formation

D. LICHEN-ACIDS 221 a. Historical b. Occurrence and examination of acids c. Character of acids d. Causes of variation in quantity and quality e. Distribution of acids

E. CHEMICAL GROUPING OF ACIDS 225 I. ACIDS OF THE FAT SERIES II. ACIDS OF THE BENZOLE SERIES SUBSERIES I. ORCINE DERIVATIVES SUBSERIES II. ANTHRACENE DERIVATIVES

F. CHEMICAL REAGENTS AS TESTS FOR LICHENS 228

G. CHEMICAL REACTIONS IN NATURE 229

II. GENERAL NUTRITION

A. ABSORPTION OF WATER 229 a. Gelatinous lichens b. Crustaceous lichens c. Foliose lichens d. Fruticose lichens

B. STORAGE OF WATER 232

C. SUPPLY OF INORGANIC FOOD 232 a. In foliose and fruticose lichens b. In crustaceous lichens

D. SUPPLY OF ORGANIC FOOD 235 a. From the substratum b. From other lichens c. From other vegetation

III. ASSIMILATION AND RESPIRATION

A. INFLUENCE OF TEMPERATURE 238 a. High temperature b. Low temperature

B. INFLUENCE OF MOISTURE 239 a. On vital functions b. On general development

IV. ILLUMINATION OF LICHENS

A. EFFECT OF LIGHT ON THE THALLUS 240 a. Sun lichens b. Colour-changes due to light c. Shade lichens d. Varying shade conditions

B. EFFECT OF LIGHT ON REPRODUCTIVE ORGANS 244 a. Position and orientation of fruits with regard to light b. Influence of light on colour of fruits

V. COLOUR OF LICHENS

A. ORIGIN OF LICHEN-COLOURING 245 a. Colour given by the algal constituent b. Colour due to lichen-acids c. Colour due to amorphous substances d. Enumeration of amorphous pigments e. Colour due to infiltration

CHAPTER VI. Bionomics

BIONOMICS

A. GROWTH AND DURATION OF LICHENS 252

B. SEASON OF FRUIT FORMATION 255

C. DISPERSAL AND INCREASE 256 a. Dispersal of crustaceous lichens b. Dispersal of foliose lichens c. Dispersal of fruticose lichens

D. ERRATIC LICHENS 258

E. PARASITISM 260 a. General statement b. Antagonistic symbiosis c. Parasymbiosis d. Parasymbiosis of fungi e. Fungi parasitic on lichens f. Mycetozoa parasitic on lichens

F. DISEASES OF LICHENS 268 a. Caused by parasitism b. Caused by crowding c. Caused by adverse conditions

G. HARMFUL EFFECT OF LICHENS 269

H. GALL-FORMATION 270

CHAPTER VII. Phylogeny

PHYLOGENY

I. GENERAL STATEMENT

A. ORIGIN OF LICHENS 272

B. ALGAL ANCESTORS 273

C. FUNGAL ANCESTORS 273 a. Basidiolichens b. Ascolichens

II. THE REPRODUCTIVE ORGANS

A. THEORIES OF DESCENT IN ASCOLICHENS 273

B. RELATION OF LICHENS TO FUNGI 275 a. Pyrenocarpineae b. Coniocarpineae c. Graphidineae d. Cyclocarpineae

III. THE THALLUS

A. GENERAL OUTLINE OF DEVELOPMENT OF THALLUS 281 a. Preliminary considerations b. Course of evolution in Hymenolichens c. Course of evolution in Ascolichens

B. COMPARATIVE ANTIQUITY OF ALGAL SYMBIONTS 282

C. EVOLUTION OF PHYCOLICHENS 283 a. Gloeolichens b. Ephebaceae and Collemaceae c. Pyrenidiaceae d. Heppiaceae and Pannariaceae e. Peltigeraceae and Stictaceae

D. EVOLUTION OF ARCHILICHENS 287 a. Thallus of Pyrenocarpineae b. Thallus of Coniocarpineae c. Thallus of Graphidineae d. Thallus of Cyclocarpineae AA. LECIDEALES aa. Coenogoniaceae bb. Lecideaceae and Gyrophoraceae cc. Cladoniaceae 1. Origin of Cladonia 2. Evolution of the primary thallus 3. Evolution of the secondary thallus 4. Course of podetial development 5. Variation in Cladonia 6. Causes of variation 7. Podetial development and spore-dissemination 8. Pilophorus, Stereocaulon and Argopsis BB. LECANORALES aa. Course of Development bb. Lecanoraceae cc. Parmeliaceae dd. Usneaceae ee. Physciaceae

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