276 Darwin, and after Darwin. 
taxonomic divisions, that the theory which accounts 
for these adaptations accounts also for the forms which 
present them,—i. e. becomes a/so a theory of the origin 
of spcctes. This, however, is clearly but an accident of 
particular cases; and, therefore, even in them the 
theory is prémarily a theory of adaptations, while it is 
but secondarily a theory of the species which present 
them. Or, otherwise stated, the theory is no more a 
theory of the origin of species than it is of the origin 
of genera, families, and the rest; while, on the other 
hand, it is everywhere a theory of the adaptive modifi- 
cations whcreby each of these taxonomic divisions has 
been differentiated as such. Yet, sufficiently obvious 
as the accuracy of this definition must appear to any 
one who dispassionately considers it, several naturalists 
of high standing have denounced it in violent terms. 
I shall therefore have to recur to the subject at some- 
what greater length hereafter. At present it isenough 
merely to mention the matter, as furnishing another 
and a curious illustration of the not infrequent 
weakness of logical perception on the part of minds 
well gifted with the faculty of observation. It may be 
added, however, that the definition in question is in 
no way hostile to the one which is virtually given by 
Darwin in the title of his great work. The Origdn of 
Species by means of Natural Selecticn is beyond 
doubt the best title that could have been given, 
because at the time when the work was published the 
fact, no less than the method, of organic evolution had 
to be cstablished; and hence the most important 
thing to be done at that time was to prove the 
transmutation of species. But now that this has been 
done to the satisfaction of naturalists in general, it is, 
