748 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



of biological tlioiight. This leaven may be described as tlie growing consciousness, 

 not yet expressed in words but evidently present in the minds of many people, 

 that the uninspiring doctrines of biological immutability must soon give way to 

 something more in tune with the spirit of the times and, it may be added, more 

 in accord with a rapidly growing body of observed facts. The spark that ulti- 

 mately fired this tamped charge was, of course, the appearance of Darwin's 

 The Origin of Species in 1859, but it is easy to see now not only that the fuse 

 had been smouldering for years, but that the study of plant geography had made 

 no small contribution to this result. 



Indeed, it may be said with truth tliat, from the point of view of this sub- 

 ject, the foundation of the California Academy of Sciences in 1853 could scarcely 

 have been at a more auspicious time, for it was followed within the short space of 

 seven years by a series of pul^lications which became classic and which, together, 

 raised the subject of plant geography to a position of special importance and sig- 

 nificance. First came Hooker's essay on the New Zealand fiora (1853), to be fol- 

 lowed two years later by A. L. P. P. de Candolle's Geographie Botaniq^ie Raison- 

 nee (1855), which still remains one of the most considerable of all such works. 

 Then, almost together, came Asa Gray's study of the flora of Japan (1859), the 

 Origin itself (1859), and Hooker's second essay, on the flora of Tasmania (1859). 

 Looking back now in the light of so much after-knowledge it is difficult 

 to recapture the intellectual atmosphere of the earlier eighteen-fifties, when the 

 scientific world was so much smaller than it is now. Such recapture is particularly 

 difficult when based on much of the contemporary literature. De Candolle's book 

 is an instance of this. Here is a closely packed study of his subject of more than 

 a thousand pages, of which the headings might serve almost equally well for 

 a survey of similar scope today and in which the author comments with judgment 

 on almost every aspect of the subject, and yet it is written entirely in what can 

 today only be called the restricted idiom of pre-evolution. Even mutability is 

 admitted, and there are discussed, more than once, the changes which species 

 may come to suffer with the passage of time. But there the curtain falls, and one 

 may search in vain for any recognition of the possibility that what may in due 

 course befall species may itself be the origin of others. It is a remarkable example 

 of scientific thought restrained by dogma. 



De Candolle's book is in many ways a striking example of one written years 

 before its time. It not only discusses many subjects the potentialities of which 

 are really only now being tested, such, as the order of families in floras or the 

 proportions between monocotyledons and dicotyledons, but, as has been said, 

 it discusses the circumstances surrounding the hypothetical creation of species 

 with considerable acumen. So much emphasis is placed on this aspect of his sub- 

 ject that one almost inevitably wonders whether the author's major premise, 

 which is the supernatural creation of species, can have been more than a piece 

 of traditionalism designed perhaps to ensure that the rest of his work would not 

 be dismissed too summarily. But this does not appear to have been the case. 

 Thistleton-Dyer (1893), in his obituary of de Candolle, suggests that it was 

 partly the influence of ideas about the climatic factors of distribution and partly 

 a somewhat unimaginative quality of mind that made him miss the essential 

 point by so narrow a margin. How near he had been to it he himself fully 

 realized later, and it is pleasant to notice in after correspondence Darwin's great 



