VI 
DIFFICULTIES AND OBJECTIONS 
137 
a danger to the animal in passing rapidly through dense 
thickets. But Sir James Hector states, that the wapiti, in 
North America, throws back its head, thus placing the horns 
along the sides of the back, and is then enabled to rush 
through the thickest forest with great rapidity. The brow- 
antlers protect the face and eyes, while the widely spreading 
horns prevent injury to the neck or flanks. Thus an organ 
which was certainly developed as a sexual weapon, has been 
so guided and modified during its increase in size as to be of 
use in other ways. A similar use of the antlers of deer 
has been observed in India. 1 
The various classes of facts now referred to serve to show 
us that, in the case of the two higher groups — mammalia 
and birds — almost all the characters by which species are 
distinguished from each other are, or may be, adaptive. It is 
these two classes of animals which have been most studied 
and whose life-histories are supposed to be most fully known, 
yet even here the assertion of inutility, by an eminent 
naturalist, in the case of two important organs, has been 
sufficiently met by minute details either in the anatomy or in 
the habits of the groups referred to. Such a fact as this, 
together with the extensive series of characters already 
enumerated which have been of late years transferred from 
the “useless” to the “useful” class, should convince us, that 
the assertion of “ inutility ” in the case of any organ or 
peculiarity which is not a rudiment or a correlation, is not, 
and can never be, the statement of a fact, but merely an 
expression of our ignorance of its purpose or origin. 2 
1 Nature, vol. xxxviii. p. 328. 
2 A very remarkable illustration of function in an apparently useless 
ornament is given by Semper. He says, “It is known that the skin of 
reptiles encloses the body with scales. These scales are distinguished by 
very various sculpturings, highly characteristic of the different species. 
Irrespective of their systematic significance they appear to be of no value in 
the life of the animal ; indeed, they are viewed as ornamental without regard 
to the fact that they are microscopic and much too delicate to be visible to 
other animals of their own species. It might, therefore, seem hopeless to show 
the necessity for their existence on Darwinian principles, and to prove that 
they are physiologically active organs. Nevertheless, recent investigations on 
this point have furnished evidence that this is possible. 
“ It is known that many reptiles, and above all the snakes, cast off the 
whole skin at once, whereas human beings do so by degrees. If by any 
accident they are prevented doing so, they infallibly die, because the old 
