Makers of British Botany; a collection of biographies by living botanists

by Unknown

On his return to England he was appointed librarian to the Linnean Society (1805), an office which he held till 1822, and he at once set about to utilise the vast resources which were now at his command.

He contributed to the narrative of The Flinders Expedition an account of the vegetation of New Holland. The essay is a remarkable one, not only for the masterly descriptions of the principal genera and orders which it contains, and the critical remarks which are scattered through the pages, but also for the geographical and statistical methods of treatment which he introduced. Many of the orders are new, and Brown shews his striking perception of affinity not only in his general discussion of the subject as a whole, but also in the definitions of the new orders and genera which he founded. This soundness of judgment is shewn on a still larger scale in his more definitely systematic works such as the Prodromus, but one may regard it generally as an astonishing tribute to his sagacity that very few of the groups founded by him have needed serious revision, even when further discoveries made it possible for later botanists to fill up the lacunae inevitable during those earlier days.

In the year 1810 there appeared the first volume of his great work, the Prodromus Florae Novae Hollandiae. It is a misfortune that only one volume was ever published, although the work was advanced in MS. It has been said that a criticism of the author's Latinity at the hands of a reviewer was the cause of the stoppage of the publication, but there seems to be no real foundation for the story. Possibly the expense, coupled with the small return, may at any rate partly account for it. Be this as it may, Brown recalled from his bookseller all the unsold copies, and in the copy preserved at the Natural History Museum there is a list of the volumes actually sold written by Brown himself, and from a financial point of view the enterprise clearly proved itself to be an expensive experiment. The volume as published is a remarkable work, containing some 450 pages, including 464 genera, nearly one-third of which are here described for the first time and the number of species amounts to about 2000, some three-quarters of which were new to science. Add to this the fact that the flora as a whole is very unlike that of the northern hemisphere, also that the work was accomplished with such amazing rapidity (largely owing to his particular methods already alluded to), and one cannot withhold admiration at the energy and the learning of its author. It is a wonderful tribute to his wisdom that his descriptions and arrangements should have so stood the test of 100 years, during which time vast strides in our knowledge of the Australian and other floras have been made. But the lapse of time has resulted in scarcely any but trifling modifications of the general results as he left them. The Prodromus is well worth study, for in its pages one constantly meets with hints of observations which have borne fruit in later years. Some of them, indeed, e.g. his observations on Cycads, were expanded by himself into larger treatises in which much light has been thrown on morphological and taxonomic relationships previously but imperfectly understood.

The year before the publication of the Prodromus, Brown communicated to the Linnean Society an excellent and learned memoir on the Proteaceae. In this paper we encounter an instance of that whimsical introduction of observations exceedingly valuable in themselves, but mainly irrelevant to the matter in hand, which is a characteristic feature of many of his works. Perhaps it was due to the intense keenness with which he always followed up problems that interested him, so that, like Mr Dick's weakness for King Charles' head, they had to find a place in whatever else he was writing about. Thus his treatise on the Proteaceae starts off with advice to study the flower in the young, instead of only in its adult condition, and this is driven home by an excellent disquisition on the structure of the androecium and gynaeceum of Asclepiads, a subject which occupied his mind for some years and formed the basis for separate papers at subsequent periods. Only when he has discussed the morphology of the Asclepiad flower does he plunge, abruptly, into the questions relating directly to the Proteaceae.

Later on in the same year (1809) he read a masterly paper on the Asclepiadaceae which was subsequently printed in the Memoirs of the Wernerian Natural History Society. This Natural Order was here separated by him from the Apocynaceae, from which it had not previously been distinguished, and a correct account of the relations of the remarkable androecium, so characteristic of the Asclepiad flower, was given. Twenty-two years later (in 1831) he again returned to the Asclepiads and described and discussed the mode of pollination and fertilisation in this Order and also in that of the Orchids.

It was characteristic of Brown that he clung with great tenacity to any problem that had once excited his interest. He made himself fully acquainted with the work of his contemporaries and predecessors, and at the same time he constantly attacked it by reiterated first-hand investigations, testing hypotheses and theories by the light of direct observation. He was very cautious, and thus, although he traced the pollen tubes from the pollen grain into the ovary and into the micropyle (foramen) of the ovule, he still leaves it an open question whether, in all cases, anything of a material nature passes from the pollen to the interior of the ovule, which may thus be held responsible for the formation of an embryo.

He cites the observations of Amici and of Du Petit Thouars, and then states he does not feel he is as far advanced as these observers. But in the succeeding pages he traces the tube, of which he says, "the production is a vital action excited in the grain by the application of an external stimulus." We see here a clear perception of the facts of germination and of the operation of what we now call chemiotaxis, for he goes on to add "The appropriate and most powerful stimulus to this action is no doubt contact, at the proper period, with the secretion or surface of the stigma of the same species. Many facts, however, and among others the existence of hybrid plants, prove that this is not the only stimulus capable of producing the effect; and in Orchideae I have found that the action in the pollen of one species may be excited by the stigma of another belonging to a very different tribe." It is hard to believe that these lines were written so long as 80 years ago. Brown goes on to describe the change that follows impregnation, and the gradual appearance of the embryo. And we must remember that all these observations were made by one who relied almost exclusively on the simple microscope and the simplest—I had almost said barbaric—technique.

He expresses himself in very reserved terms as to the nature of the "immediate agent derived from the male organ, or the manner of its application to the ovulum in the production of that series of changes constituting fecundation." But he puts forward the opinion that a more attentive examination of the process in Orchids and Asclepiads is more likely to be fruitful of results than most other families.

He returns again to this matter of fecundation in the following year, studying several orchids, but especially Bonatea, for the purpose. He is somewhat shaken as to the validity of his former inferences, and concludes that the "mucous cords" (i.e. strings of pollen tubes) are perhaps derived from pollen "not, however, by mere elongation of the original pollen tubes, but by an increase in their number, in a manner which I do not attempt to explain." In this later paper he also hazards the suggestion that in Ophrys, as impregnation is frequently accomplished without the aid of insects, "... it may be conjectured that the remarkable forms of the flowers in this genus are intended to deter, not to attract, insects." Also he suggests that the insect forms in orchidaceous flowers resemble those of the insects belonging to the native country of the plants. This is a clear foreshadowing of what is now called protective mimicry—and the former suggestion is not at any rate wholly without modern supporters, though Brown's share in its origin seems not to be generally recognised.

The keen desire to get to the bottom of a problem, which was so outstanding a feature of Brown's whole mental attitude, unquestionably explains why he was led to make so many important discoveries in such widely different directions. His first hand knowledge of the structure of a vast number of plants gave a soundness and depth to his morphological investigations that must arouse the admiration of everyone who is acquainted with them. He was never satisfied with perfunctory attempts to solve a problem, but, as we have already seen, in the example of his studies on Asclepiads and Orchids, he would return again and again to the matter till he had satisfied himself of the accuracy of his work. It is a pity that all of the present day botanists do not follow more closely in his steps in this respect. Publication of a paper seems to some to be a matter of greater importance than the advance of knowledge by the scientific and scholarly solution of a problem. Such was not Brown's view, and he practised wise delay in publication—nonumque prematur in annum, a maxim so strongly advocated by the Latin poet, was really put into practice by him as it also was by some of his contemporaries. Dryander, Solander and others have left, as Brown has done, rich stores of MS. behind them, which have never passed through the press.