GOOD; PLANT GEOGRAPHY 751 



interesting parallels. Bach was early attracted by geographical problems and 

 retained his interest in these throughout his long life. But both later devoted 

 themselves especially to systematics, Hooker's work in this field culminating (in 

 collaboration with Bentham) in the Genera Plantarum (1862-1883) and in a 

 number of floras, of which that of British India is preeminent (1875-1897), 

 Engler's work in his well-known Syllabus (11th ed., 1936), and in the editing 

 of such great undertakings as the Naturlichen Pflanzenfamilien (Engler and 

 Prantl, 1889-1924) and Das PflanzenreicJi (Engler, 1900). Much the same is 

 true, too, of de Candolle, whose energies were later deeply absorbed in the con- 

 tinuance of his father's Prodromus (A. P. and A. L. P. P. de Candolle, 1824-1873) . 



Drude was perhaps in the more direct geographical succession, and in par- 

 ticular will always be remembered for his Atlas der Pflanzenverhreitung. This 

 was published in 1887 as part of a larger physical atlas and consisted of a short 

 series of excellently produced maps showing the ranges of various important 

 plant elements, both vegetational and floristic, accompanied by a concise explana- 

 tory letterpress. The work of Drude, however, is more generally known from his 

 Handhuch der PflanzengeograpJiie, which appeared in 1890 and contained among 

 other things an improved floristic classification. This, however, though an im- 

 portant book, said little that was entirely new and gives the impression rather 

 of belonging to the end of an epoch. 



It is very noticeable, in the gradual development of a science, how often 

 progress takes the form of successive pulsations, each giving great impetus to the 

 study for a time but then tending to lose momentum, being replaced in due course 

 by some new intensification along some rather different line. Thus it would seem 

 that by the eighteen-nineties the forward urge provided by Darwinism had begun 

 to work itself out and that some new impulse was due. This came in the form 

 of a concentration upon the relation between the plant and its immediate 

 environment or habitat, a new approach or point of view to which was given 

 the name "plant ecology," or "oecology," as it was first spelled. The first 

 principles of this new discipline, which, as we shall see, has since become the 

 sister of the older plant geography in the stricter sense, were set forth in two 

 books which were, effectively, more or less contemporaneous. These were Warm- 

 ing's Plantesamfund, published in Denmark in 1895 and later translated into 

 the more familiar Oecology of Plants, and Schimper's Pflanzen-Geographie auf 

 Physiol ogische Grundlage (1898), which also was translated into English some 

 years later. 



There is no doubt that a powerful influence in the hiving off of plant ecology 

 was the reaction against the aridity which had affected much of botany through 

 an overemphasis on formal morphology. It may be said to have been based on 

 two fundamental propositions : that the plant itself is a living organism in close 

 and intimate relation, both functionally and structurally, with the conditions 

 of its environment, and that vegetation is a dynamic complex expressing the 

 same laws of universal change with time as everything else in nature. Schimper 

 himself expressed this idea (loc. eit.) when he said that the problems of plant 

 geography will not be exhausted when the world flora is completely known (a 

 contingency which, strangely enough, he seems to have thought imminent) but 

 will become of a rather different sort and particularly concerned with the 

 explanations of the differences between floras in different parts of the world. 



