DEVELOPMENT OF BOTANY SINCE 1818 453 



zone, during the Tertiary period, or the Cretaceous which 

 preceded it, and the descendants had made their way 

 down different lines toward the south, the species vary- 

 ing under different climatic conditions, and thus exhib- 

 iting similarity but not absolute identity of form. Before 

 the American Association for the Advancement of Sci- 

 ence, in his Presidential address, in 1872, he used the 

 following language : 



"According to these views, as regards plants at least, the 

 adaptation to successive times and changed conditions has been 

 maintained, not by absolute renewals, but by gradual modifica- 

 tions. I, for one, cannot doubt that the present existing species 

 are the lineal successors of those that garnished the earth in the 

 old time before them, and that they were as well adapted to 

 their surroundings then, as those which flourish and bloom around 

 us are to their conditions now. Order and exquisite adaptation 

 did not wait for man's coming, nor were they ever stereotyped. 

 Organic Nature by which I mean the system and totality of 

 living things, and their adaptation to each other and to the 

 world with all its apparent and indeed real stability, should 

 be likened, not to the ocean, which varies only by tidal oscilla- 

 tions from a fixed level to which it is always returning, but 

 rather to a river, so vast that we can neither discern its shores 

 nor reach its sources, whose onward flow is not less actual 

 because too slow to be observed by the ephemeras which hover 

 over its surface, or are borne upon its bosom." 



Gray's active interest in the Journal continued until 

 the very end of his life. There were many critical 

 notices from his pen in 1887. His last contribution to its 

 pages was the botanical necrology, which appeared post- 

 humously in volume 35, of the third series (1888). His 

 connection with the Journal covered, therefore, a period 

 of more than a half a century of its life. 2 



The changes that were wrought in botany by the 

 application of Darwinism were far reaching. Attempts 

 were promptly made to reconstruct the system of botan- 

 ical classification on the basis of descent. The more suc- 

 cessful of these endeavors met with welcome, and now 

 form the groundwork of arrangement of families, genera, 

 and species, in the Herbaria in this country, in the man- 

 uals of descriptive botany, and in the text-books of higher 

 grade. This overturn did not take place until after 



