252 Evolution and Adaptation 
unable to find any statements of this sort in Lamarck’s 
writings. 
The following cases that Darwin tried to explain through 
the inheritance of acquired characters are exactly like those 
to which Lamarck applied his theory. The bones of the 
wing of the domestic duck weigh less than those of the wild 
duck, and the bones of the leg more. Darwin believes this 
is due to the effects of the inheritance of acquired characters. 
The drooping ears of many domestic mammals are also 
explained by him as a result of disuse — “the animals being 
seldom much alarmed.” In speaking of the male of the 
beetle, Onztes apelles, Darwin quotes Kirby to the effect that 
the tarsi are so habitually lost that the species has been 
described without this part of the foot. In the sacred beetle 
of Egypt the tarsus is totally absent. Hence he concludes 
that the absence of tarsi in the sacred beetle, and the rudi- 
mentary condition of the tarsus in others, is probably the 
result of disuse, rather than a case of inheritance of a muti- 
lation. Darwin grants that “the evidence that accidental 
mutilations can be inherited is at present not decisive, but 
the remarkable case observed by Brown-Séquard in guinea- 
pigs of the inherited effects of operations should make us 
cautious in denying this tendency.” 
The wingless condition of several insects inhabiting oceanic 
islands has come about, Darwin thinks, through disuse. The 
ostrich also, owing to its increase in size, made less use of its 
wings and more use of its legs, with the result that its wings 
degenerated and its legs got stronger. The rudimentary 
condition of the eyes of the mole is the result of disuse, 
“aided perhaps by natural selection.” Many of the ani- 
mals inhabiting the caves of Kentucky and of Carniola 
are blind, and this is ascribed to disuse. “As it is diffi- 
cult to imagine that the eyes, though useless, could be in 
any way injurious to animals living in darkness, their loss 
may be attributed to disuse.” The long neck of the giraffe 
