Part 26

But the centre of the Garden for reference and for detailed study is now the herbarium and library, housed in the large building near to the entrance from Kew Green. To those familiar with that magnificent mine of accumulated learning as it now stands, it may be a surprise to hear that it has grown in the course of less than 60 years out of the private collections of Sir William Hooker, and of his friend Bentham. The story of it may be gathered from the sketch of the Life and Labours of the First Director, published by Sir Joseph Hooker in the Annals of Botany in 1903, a work to which I have been largely indebted for the materials for this lecture. The Hookerian herbarium and library were already extensive before it was removed from Glasgow. When the new Director of Kew took up his appointment, neither books nor a herbarium were provided for him: but he was well equipped with those of his own. They were at first lodged in his private house, till in 1853 he moved into the official residence. But the latter did not afford the accommodation for them which the Government had guaranteed. They were therefore placed in a building adjacent to the Botanic Garden. It was further agreed, on condition that the herbarium and library should be accessible to botanists, that he should be provided with a scientific herbarium Curator. Four years afterwards the Royal Gardens came into possession, by gift, of the very extensive library and herbarium of G. Bentham, Esq., which was second only to Hooker's own in extent, methodical arrangement, and nomenclature; and it was placed in the same building. The two collections in considerable degree overlapped, being derived from the same sources. But one great difference between them was that Bentham confined his herbarium to flowering plants, while Hooker's rapidly grew to be the richest in the world in both flowering and flowerless plants. Finally after his death it was acquired by purchase for the State in 1866, together with about 1000 volumes from his library, and a unique collection of botanical drawings, maps, MSS., portraits of botanists, and letters from botanical correspondents, which amounted to about 27,000. These were the prime foundations of the great herbarium and library now at Kew. Great additions have since been made by purchase and by gift, and the building has been repeatedly extended to receive the growing mass of material. But for all time the character and individuality of the collections will remain stamped by the personality of those two great benefactors, Bentham and the first Hooker.

Sufficient has now been said to indicate that Hooker's work was that of a pioneer, in providing the material foundation necessary for the further study of the science, not only in this country, but also in the furthest lands of the Empire. He supplied a coordinating centre for botanical organisation in Britain, and for that service he has earned the lasting gratitude of botanists. It remains to review his own published works, and base upon them some estimate of his more direct influence upon the progress of the science. We shall see that in this also his work was largely of that nature which affords a basis for future development. It was carried out almost entirely under pre-Darwinian conditions. He was pre-eminently a descriptive botanist, who worked under the influence of the current belief in the constancy of species. But his enormous output of accurate description and of delineation of the most varied forms, has provided a sure basis upon which the more modern seeker after phyletic lines may proceed.

There have been few if any writers on botanical subjects so prolific as Sir William Hooker, and probably none have ever equalled him in the number and accuracy of the plates which illustrated his writings. Sir Joseph Hooker estimates the number of the latter at nearly 8000, of which about 1800 were from drawings executed by himself. The remainder were chiefly from the hand of Walter Fitch, who acted as botanical limner to Sir William for thirty years, showing in the work fidelity, artistic skill and extraordinary rapidity of execution. The numbers quoted give some idea of the magnitude of the results.

For the purpose of a rapid review of the chief writings of Sir William's later years, they may be classified under three heads, viz. (1) Journals, (2) Floristic works, and (3) Writings on the Filicales. Taking first the Journals, one of the most remarkable features about them is the apparent variety and number of the enterprises on which Sir William engaged: this is, however, explained when they are pieced together as they will be found below. His connection during 45 years with large and growing gardens, into which the most varied living specimens were being drafted in a constant stream, put him in possession of a vast mass of facts, detached, but needing to be recorded. The materials were thus present for that type of publication styled a Botanical Miscellany. The majority of the serials which he edited took this form, and though published under various titles, dictated in some measure by the source of their publication, more than one of them was a mere continuation of a predecessor under a different title. The first of them appeared under the name of the Exotic Flora, in three volumes (1823-7), with 232 coloured plates illustrating subjects from the Gardens of Glasgow, Edinburgh, and Liverpool. But owing to his taking up in 1827 the editorship of the Botanical Magazine, then in a critical position, the Exotic Flora ceased, and its materials swelled the pages of the more ancient serial, with which he was connected till his death.

To those not intimately acquainted with the other serials edited by Sir William, their relations are difficult to trace. But Sir Joseph Hooker has given their titles in series, with their dates, as follows:

Botanical Miscellany. 3 vols. 1830-33. Journal of Botany. 1 vol. 1834. Companion of the Botanical Magazine. 2 vols. 1835-36. Jardine's Annals of Natural History. 4 vols. 1838-40. The Journal of Botany (continued). Vols. II.-IV. 1840-42. The London Journal of Botany. 7 vols. 1842-48. The Companion of the Botanical Magazine. (New Series. 1845-48.) London Journal of Botany and Kew Gardens Miscellany. 9 vols. 1849-57.

From this list it appears that throughout a long term of years, though under varying titles, the stream of information gathered chiefly through garden management was edited and published, taking the form of 28 volumes, with 556 plates.

The "Floristic" works of Sir William Hooker began with the second edition of Curtis's Flora Londinensis, in five folio volumes, upon which he worked from 1817 to 1828. He contributed a large proportion of the plates from his own drawings, while the descriptions throughout (excepting those of the plates on Algae and Fungi by R. K. Greville) were enlarged, and rewritten by him. He was in fact the real author of the work, which, however, was so badly edited--even the letter-press was not paged--that citation of it was impossible, and it never took its proper place as a scientific work. Sir Joseph Hooker points out that the second edition was not properly styled Flora Londinensis, since it included many species which are not indigenous anywhere near London. But these were the lapses of the editor, not of the author and artist. Minor works were the accounts of the plants collected on Parry's and Sabine's Arctic voyages (1823-28), but the Flora Boreali Americana was a more important undertaking. It appeared as two quarto volumes (1829-40), in which 2500 species were described with numerous illustrations. It was based on the collections of various travellers, and included ferns and their allies. In 1830 came the first edition of the British Flora, a work which was continued through eight editions, the last being in 1860, and it contained 1636 species. The botanical results of Beechey's voyage in the "Blossom" to the Behring Sea, the Pacific Ocean, and China were produced jointly with Dr Walker-Arnott in 1830-41, as a quarto volume, with descriptions of about 2700 species, and notable for the diversity of the floras included. In 1849 the Niger Flora appeared, dealing with the collections of Vogel on the Niger expedition of 1841. But the most remarkable of all these floristic works was the great series of the Icones Plantarum. It was initiated in 1837 for the illustration of New and rare plants selected from the Author's Herbarium, and was continued by him till his death in 1865. Owing to the munificence of Bentham's bequest to the Kew Herbarium for its continuance and illustration, it remains still as the principal channel for the description and delineation of new and rare plants from the Kew Herbarium. The fact that the number of the plates is now about 3000 gives some idea of the magnitude of this work, which was started by Sir William Hooker in the later days of his Glasgow professorship.

It might well be thought that the production of the works already named would have sufficed to occupy a life-time, especially when it is remembered that they were produced in the intervals of leisure after the performance of the official duties of a professor, and later of the Director of the growing establishment at Kew. But there still remain to be mentioned that noble series of publications on the Filicales, which gave Sir William Hooker the position of the leading Pteridologist of his time. The series on ferns began with the Icones Filicum (1828-31) in two folio volumes, with 240 coloured plates by R. K. Greville, the text being written by Hooker. The same authors again cooperated in the Enumeratio Filicum (1832), a work projected to give the synonymy, citation of authors, habitat, and description of new and imperfectly known species. But it only extended to the first 13 genera, including the Lycopodineae, Ophioglosseae, Marattiaceae, and Osmundaceae, and was then dropped. Here may be conveniently introduced a number of volumes, which were for the illustration of ferns, but not systematically arranged. They were issued from time to time, and collectively give a large but not a coordinated body of fact. They were, the First Century of Ferns, issued in 1854; the Filices Exoticae in 1859; a Second Century of Ferns in 1861; British Ferns also in 1861, and Garden Ferns in 1862.

There still remain to be mentioned three great systematic works on ferns, each of which is complete in itself, viz. the Genera Filicum, the Species Filicum, and the Synopsis Filicum. The first of these was the Genera Filicum (1838-40), a volume issued in parts, royal octavo, with 126 coloured plates illustrating 135 genera. It goes under the joint names of Francis Bauer and Sir William Hooker, the latter being described on the title-page as Director of Kew. But the preface is dated May 1, 1838, from Glasgow, and it was printed at the University Press. The title-page further states that the plates were from the drawings of F. Bauer, but Sir Joseph Hooker points out (l.c. p. cviii), that "of the whole 135 genera depicted I think that 78 are by Fitch." Sir William in the preface states that "The plates have all been executed in my own residence, and under my own eye, in zincography, by a young artist, Walter Fitch, with a delicacy and accuracy which I trust will not discredit the figures from which they were copied." The result is one of the most sumptuous volumes in illustration of a single family ever published. After 70 years it is still the natural companion of all Pteridologists. At its close is a synopsis of the genera of ferns, according to Presl's arrangement, which Sir William describes as "the most full and complete that has yet been published." But in the preface he remarks that Presl "has laid too much stress on the number and other circumstances connected with the bundles of vessels in the stipes, which in the Herbarium are difficult of investigation." This is a specially illuminating passage for us at a time when anatomical characters are becoming ever more important as phyletic indices. It shows that readiness of diagnosis was for him a more important factor than details of structural similarity.

In the preface to the Genera Filicum Sir William says, he "would not have it to be understood that the Genera here introduced are what I definitely recommend as, in every instance, worthy of being retained.... A more accurate examination of the several species of each Genus, which are now under review in the preparation of a Species Filicum, will enable me hereafter to form a more correct judgement on this head than it is now in my power to do." The five volumes of the Species Filicum thus promised, appeared at intervals from 1846 to 1864. The work is briefly characterised by Sir Joseph as consisting of "descriptions of the known Ferns, particularly of such as exist in the Author's Herbarium, or are with sufficient accuracy described in the works to which he has had access, accompanied by numerous Figures. This which will probably prove to be the most enduring monument to my father's labour as a systematist and descriptive pteridologist, is comprised in five 8vo volumes, embracing nearly 2500 species, with 304 plates by Fitch, illustrating 520 of these. It occupied much of the latter eighteen years of his life, the last part appearing in 1864." The work is a most extraordinary mine of detailed information. It is a condensed extract from his own unrivalled Herbarium of Ferns, with exact data of distribution, and collectors' numbers. Probably no family so extensive as this has ever been monographed by a single hand with such minuteness and exhaustive care. It is the classic book of reference in the systematic study of ferns. But as indicated in the preface to the Genera, the judgement as to which genera are "worthy of being retained" had been exercised. The result was the merging of a number of the genera of Presl, and others, into neighbouring genera. Though this was somewhat drastically done in the Species Filicum, it comes out more prominently in the work upon which he entered in the very last months of his life, viz. the Synopsis Filicum. This work was published in 1868 as an octavo volume, with 9 coloured plates, containing analyses of 75 genera. Sir Joseph tells us (l.c. p. 117) that "Upon this work my father was engaged up to a few days before his decease, and 48 pages of it in print were left on his desk, together with the preface and much matter in manuscript. After full consideration it appeared to me that, with the material in hand, the aid of the Species Filicum completed only three years earlier, and of the Fern Herbarium in perfect order, and named according to his views, a competent botanist should find no great difficulty in carrying on this work to its completion. Such a botanist I knew my friend Mr Baker to be, and also that he had made a study of Ferns, and accepted my father's limitations of their genera and species. I therefore requested that gentleman to undertake the work, which to my great satisfaction he has done. The Synopsis Filicum contains 75 genera, and about 2252 species, inclusive of Osmundaceae, Schizaeaceae, Marattiaceae, and Ophioglossaceae, which are not included in the Species Filicum." This work summarised the Pteridological results of Sir William Hooker's life. The total number of plates of ferns published by him is about 1210, embracing 1267 species, of which about 250 appeared under the joint authorship of Dr Greville and himself. These figures are in themselves sufficient evidence of the extent of his Pteridographic work.

It has been noted that the number of genera in the Genera Filicum was 135, maintained approximately according to the limitations of Presl in his Tentamen Pteridographiae: allowance has, however, to be made for 23 genera of Parkeriaceae, Schizaeaceae, Osmundaceae, Marattiaceae, Ophioglossaceae, and Lycopodiaceae, which were omitted in the Tentamen. But in the Synopsis Filicum there were only 75. It is true that the three genera of Lycopodiaceae were excluded also from the Synopsis, but still there is the wide discrepancy between 132 of Presl's genera as against 75 in Hooker's Synopsis. This at once indicates a salient feature of his method. He merged a large number of genera, ranking many of the smaller ones as sub-genera under the more comprehensive headings. Doubtless the reasons for this were various. One was his mistrust of anatomical data, which it must be confessed Presl put too much in the fore-front. The very first sentence of the Tentamen runs thus "Vasa plantarum principale signum esse ex eo patet, quod exinde primaria divisio omnium plantarum exstitit." But occasionally Sir William explained his reason in a specific case. Thus in the question of Kunze's sub-genus Plagiogyria of the genus Lomaria, which Mettenius had raised to the dignity of a distinct genus, he explained his reasons for merging it into the genus Lomaria. Mettenius had laid stress upon various characters, but especially on the oblique annulus as distinctive. On this Hooker remarks "even should the capsules in all the species referred to Plagiogyria prove to be helicogyrate, yet the habit and sori are so entirely in accordance with true Lomaria that, unless the student has the opportunity of examining very perfect specimens, or unless he examines the structure of the annulus of the very minute capsules under the high power of the microscope, the genus cannot be identified. Kunze only proposed to form a group or section under the name of Plagiogyria, but even that would be found inconvenient to retain in a work whose main object is to assist the tyro in the verification of genera and species: and natural habit is often a safer guide than minute microscopic characters." Thus we see that in his method convenience of diagnosis is put before the use of important structural characters. I have recently found reason to uphold the opinion of Mettenius on this point, and to confirm Plagiogyria as a substantive genus.

Similarly, the genera Lophosoria and Metaxya will have to be detached from Alsophila: Prantl removed Microlepia from Davallia into his new family of the Dennstaedtiinae, where they are related with Patania (Dennstaedtia), which Hooker had merged into Dicksonia. Goebel also has detached Hecistopteris which Hooker had placed in Gymnogramme, and has placed it with the Vittarieae. These are all examples of the way in which further study is tending to reverse the excessive merging of genera, which Hooker carried out in the interest of diagnostic convenience.

The general conclusion which we draw from contemplating Sir William Hooker's work on the systematic treatment of ferns is that it was carried out consistently to the end under the influence of the current belief in the Constancy of Species. The methods were not phylogenetic, as they have since become under the influence of evolutionary belief. The problem seems to have been to depict and describe with the utmost accuracy the multitudinous representatives of the Filicales, and to arrange them so that with the least possible difficulty and loss of time any given specimen could be located and named. But the result is not to dispose them in any genetic order. Even the arrangement of the larger genera according to the complexity of branching of the leaves appears as a method of convenience rather than of genesis, and subsequent inquiry is tending to show that so far as such series really exist, they will require to be read in converse. Goebel, in his paper on Hecistopteris, remarks that "the systematic grouping of the Leptosporangiate Ferns, as it is at present, e.g. in the Synopsis Filicum, is artificial throughout; it is adequate for the diagnosis of Ferns, but it does not give any satisfactory conclusion as to the affinity of the several forms." He proceeds to say that "a thorough investigation, taking into account the general characters of form of both the generations, will be necessary before the naturally related groups, and their relations to one another, are recognised in the plexus of forms of the Polypodiaceae."

Such observations as these must not be understood in any sense of disparagement of the work of this great man. They are merely intended to indicate his historical position. The Origin of Species was, it is true, published some few years before the Synopsis Filicum. But we must remember that Sir William Hooker was already an old man. Few men over 70 years of age alter their opinions, and the labourer who had grown old under the belief in the Constancy of Species could not in a few brief years be expected to change the methods of thought of a long and active life. We must take Sir William Hooker as perhaps the greatest and the last of the systematists who worked under the belief in the Constancy of Species. Because we have adopted a newer point of view, and take into consideration facts and arguments which were never his, and come to different conclusions now, is no reason for valuing one whit the less the achievements of this great botanist.

His published work was just as much fundamental as was his official work. We have seen how he provided in Kew the means of indefinite development later, by constructing the coordinating machine with its collections and its libraries. In somewhat similar sense his publications were also fundamental. He did not himself construct. There is, I believe, no great modification of system or of view which is to be associated with his name. But in the wealth of trustworthy detail, recorded both pictorially and in verbal diagnoses, he has supplied the foundation for future workers to build upon, laid surely and firmly by accurate observation, and therefore durable for all time.

One remark I may make as to the effect of his work on the trend of botanical activity in this country. We have noted that anatomy was not Sir William Hooker's strong point. He and many of his contemporaries did not pursue microscopic detail, and indeed seem to have avoided it. He was, however, a dominating botanical influence of the middle Victorian period. May we not see in these facts, combined with the extraordinary success of the systematic work carried on by himself, or under his guidance, a probable cause of that paralysis of laboratory investigation which ruled in Britain till the early seventies? British botany was at that time almost purely descriptive. The revival came within 10 years of the death of Sir William, and it is well to remember that the immediate stimulus to that revival was given by a botanist, who became later the Director of Kew, and was allied by marriage with Sir William Hooker himself. I mean, Sir William Thiselton-Dyer. The stimulus had its result in the active development of anatomical and physiological study of plants, as we see it in this country to-day. For a time the swing of the pendulum in this direction was too extreme and exclusive. I remember very well an occasion when Sir Joseph Hooker said to me, "You young men do not know your plants." And it was true, though it may be added that few indeed, at any time, knew them in the full Hookerian sense. A saner position is gradually being attained. But even now the systematic study of Angiosperms receives far too little attention among us, and is an almost open field for the young investigator.

I would conclude with one word of advice, which naturally springs from contemplation of a life-work such as Sir William Hooker's. We sometimes see wide-reaching phyletic conclusions advanced by writers who we know have not specific knowledge of the groups in question. Let us learn from Sir William the importance of specific knowledge. It is only on such a foundation that sound phyletic argument can proceed. Let us always remember that it is better to carry out sound work on species, as he did, without theorising on their phyletic relations, than to promulgate phyletic theories without a sufficient specific knowledge of the families themselves. The former will probably be lasting work, the latter runs every chance of early refutation. Under the most favourable circumstances analytical work is as a rule more durable than synthetic. Sir William Hooker's contributions fall chiefly under the former head, and will be found to have a corresponding element of durability.

JOHN STEVENS HENSLOW

1796-1861

BY GEORGE HENSLOW

An all-round man--appointed Professor of Mineralogy at Cambridge in 1826, but succeeds Martyn in the Chair of Botany a year later--essentially an ecologist--his famous teaching methods--"practical work"--his wide interests--country life--the educational museum--village amenities.

The scientific career and parochial life of the late Rev. Prof. J. S. Henslow, are described by my late uncle, the Rev. Leonard Jenyns, in his Memoir. I propose adding and illustrating some of his more personal traits, habits and pursuits as a scientific man, and to deal especially with his educational methods. His studies in science were by no means confined to one branch, thus Geology was first ardently pursued in conjunction with Sedgwick. It was in a tour together in the Isle of Wight in 1819, that they proposed establishing a "Corresponding Society, for the purpose of introducing subjects of natural history to the Cambridge students." The outcome of this idea, which was subsequently abandoned, was the "Cambridge Philosophical Society," of which "Henslow, B.A. was elected secretary in 1821."

Conchology and Entomology claimed his attention; one of his first discoveries was the rare insect Macroplea equiseti, his identical "find" being figured in Curtis' British Entomology, while he found the bivalve Cyclas Henslowiana, so named by Dr Leach, at Baitsbite on the Cam. His first and best collection of insects was presented to the Cambridge Philosophical Society. Other discoveries were made in after years, and are referred to by Jenyns.

On the death of Dr E. D. Clarke, he offered himself for the Professorship of Mineralogy. Chemistry, as well as the study of Minerals, now occupied his attention. He was only 26 years of age, and still B.A., when elected to that chair. At the age of 27 he published his Syllabus of Mineralogy in 1823, "A useful manual of reference to all persons studying Mineralogy, independently of the immediate circumstances which led to its publication."

In 1827 Prof. Martyn died and Prof. Henslow was elected to the chair of Botany, being succeeded by Whewell on resigning the Professorship of Mineralogy. He now turned his attention to the study of Botany; but he never paid much heed to systematic botany, for his taste lay in the direction of what is now called Ecology. He then wrote "Botanists would rather receive one of our most common weeds from a newly-discovered or newly-explored country, than a new species of an already known genus. There are higher departments of Botany than mere collectors of specimens are aware of; for to ascertain the geographical distribution of a well-known species is a point of vastly superior interest to the mere acquisition of a rare specimen." À propos of this he made elaborate epitomes of the Botanical Geographies of De Candolle, and of the writings of Humboldt, Poiret and others. His MS. is not unlike a fore-runner of Schimper's Botanical Geography of to-day. He thus expressed himself in the Introduction to his Descriptive and Physiological Botany (1836):--in the second section headed Botany ... "This enquiry should extend as well to the investigation of the outward forms [of plant organs] and the conditions in which plants, whether recent or fossil, are met with, as to the examination of the various functions which they perform whilst in the living state and to the laws by which their distribution on the earth's surface is regulated." Again, in the Preface to the Flora of Suffolk by himself and E. S. Skepper, he wrote:--"We had thought of saying something in regard to the Geographic distribution of the species, but found our material insufficient for treating this question to advantage." As an alternative he suggests interleaving the 'Catalogue,' as the book was also called, in which observers could add observations on the Geological formations and superficial soils upon which each species grows, e.g. Chalk, the Crags, Gravels of post-tertiary period, &c. as well as maritime, marshy, boggy, healthy and cultivated soils.

Though he wrote against mere collecting, he was an insatiable collector himself; but it was always with some definite, useful and generally educational purpose, and the best of his collections invariably went to museums, especially those of the Philosophical Society of Cambridge, of Kew and of Ipswich. The first still has the fishes he collected at Weymouth in 1832, solely for his brother-in-law L. Jenyns, the author of The British Vertebrate Animals.

One of the first things to which his attention was directed was the Cambridge Botanic Garden. It was far too small and in the centre of the town, where the scientific buildings are now erected. He urged the necessity of a new one, but it was not till 1831 that the present site was secured; the first tree, however, was not planted until 1846.