122 DUDLEY MEMORIAL VOLUME 



to describe these facts and relations as they actually are. Then we have to 

 find out what changes we can work in individuals and species by such altera- 

 tions of conditions as experiment can give. 



We do not know actually any species of animal or plant until we know 

 all changes that would or could take place in its individuals under all condi- 

 tions of environment. 



P. S. — Since this was written I have received the charming sketch of 

 Linnffius by Professor Edward Lee Greene. In a discussion of Linnaeus 

 as an evolutionist Mr. Greene shows very clearly that the great botanist 

 had in mind the same fact as to the relation of species which I have in- 

 dicated in this paper. In a note on Thalictrum lucidum referring to the 

 geminate form, he says, "This plant is possibly not very distinct from 

 T. flavum. It seems to me to be the product of its environment." Of these 

 species of meadow rue, flavum belongs to the cool moist meadows of northern 

 Europe, and lucidum to southern France and Spain. 



Referring again to the seaside Virgin's Bower, Clematis maritima, he 

 says, "Magnol and also Ray have adjudged this to be a variety of C. fiam- 

 mula. I should rather think it is derived from C. recta under altered 

 conditions." 



As to the Siberian yarrow, as compared to the common yarrow of 

 Europe, he says, "May not the Siberian mountain soil and climate have 

 moulded this out of A. ptarmica?" 



Comparing two species of Kosteletzkya (Hibiscus), one from the Adri- 

 atic region, the other from the salt marshes of our southern states, he asks, 

 "May not the Venetian species have sprung from the Virginian?" 



Dr. Greene mentions other cases of a similar sort, but these will show 

 that the idea of geminate species split off from the parent by separation and 

 changed conditions was present with the great botanist. 



