8 LIVERPOOL BIOLOGICAL SOCIETY. 
logical selection. The individuals of a species vary in 
different directions around a centre, and therefore in any 
one line which is favourable there will usually be several 
more or less marked variations. 
Now we must turn to Dr. Romanes’ third objection to 
natural selection as a theory of the origin of species, and 
that is what is known as the inutility of specific characters, 
viz. that species are often distinguished by minute charac- 
teristics which cannot serve any useful purpose, and 
therefore cannot have been produced by the action of 
natural selection. This is a matter upon which the 
practical naturalist, and the practical naturalist only, can 
express an opinion. In a letter* to Sir J. D. Hooker, 
Darwin says, ‘“‘ How painfully (to me) true is your remark, 
that no one has a right to examine the question of species 
who has not minutely described many.” It is only the 
naturalist who is intimately acquainted with the charac- 
teristics and habits of species who can realize how 
ignorant we still are of the precise use of many organs, or 
variations of organs, and who can appreciate the fact that 
many parts may be of considerable importance although 
we do not yet understand how. Romanes says that if the 
majority of specific distinctions were useful we might 
believe the rest to be so also. Well, I am bold enough to 
say that I believe the majority of specific characters to be 
of utilitarian significance, or, what is the same thing so far 
as the action of natural selection is concerned, to be co- 
related with other characters which are of importance. 
The more deeply one studies any group of animals the 
more one sees the object of the specific modifications. In 
the Tunicata, the class I have paid most attention to 
lately, I am convinced of the practical importance of the 
specific characters, such as the condition of the muscular 
* Life and Letters, vol. ii., p. 39. 


