BOTANY. 209 



All these newly isolated colonists will be affected 

 by the physical characteristics of their new home, 

 and, of course, all will either adapt themselves in 

 some way to them or die out. It does not follow 

 that these adaptations will be the same in every 

 case. There may be two or three or more main 

 directions in which they are made to vary. 



Thus, to recur to the original instance, plants 

 which have been accustomed to flower, say, in the 

 beginning of the rainy season may, if they arrive 

 in the Victoria region, begin to flower either in 

 November or in February. Under certain circum- 

 stances the differences in, for example, temperature 

 between November and February may produce in 

 both these sets of the same species visible dif- 

 ferences which may be sufficient to make them in 

 an ordinary botanist's eyes species, distinct both 

 from their parent and from one another. Under 

 no circumstances can they cross if they are 

 specialised to flower in these different months.* 



From this one sees clearly that the first essential 



* In the preceding remarks I am obliged to assume what 

 has never been questioned by any one except Professor 

 Weissmann. Those who have studied Darwin's " Plants 

 and Animals under Domestication," or who have watched 

 the curious wrigglings and formation of new heads which 

 Weissmannism adopted under the strain of adverse facts, will 

 not require any further apology. Mr. Herbert Spencer has 

 very satisfactorily buried its remains in two articles in the 

 Contemporary Review. Professor Henslow has, since the above 

 was written, proved most of the theory which is embodied in 

 the above " Origin of Plants." 



15 



