XVI ARE ACQUIRED CHARACTERS INHERITED? 343 



Thus, whenever some great change of conditions led to a 

 more severe struggle for existence, the modifications of 

 structure needed for adaptation to the new environment 

 would soon be effected without any aid from use- 

 inheritance. 



That this is the fact is further indicated by the large 

 range of characters and adaptations that must have been 

 produced by variation and selection alone, since use- 

 inheritance cannot possibly have had any part in their 

 development. Mr. Spencer admits that there are many 

 such, but does not recognise the weight of the argument 

 which they afford against the need of use-inheritance 

 as a factor in evolution. It is well, therefore, briefly to 

 enumerate some of the more important of them. We 

 have already referred to the teeth, in their numerous 

 peculiarities of form, structure, and mode of gTowth, many 

 of which are quite removed from any direct influence of 

 use in their production. Still less can we impute the hair 

 to such causes, in its varieties of length, thickness, texture, 

 and colour, with its occasional modification into protective 

 armour, such as plates, scales, or spines, or into offensive 

 weapons, such as the horns of the rhinoceros. The bills 

 of birds, in such strange modifications as are presented in 

 the duck, the spoonbill, the heron's spear, the woodpecker's 

 chisel, the snipe's sensitive borer, the enormous but very 

 light bill of the toucan, the powerful nut-cracking bill of 

 the cockatoo, and many others, all evidently adapted to 

 special uses, but by no possibility developed by those 

 uses ; the wonderful modifications of the stomach in 

 ruminants, and especially in the camels ; the whole series 

 of protective, warning, and recognition colours of animals ; 

 the numerous peculiarities of structure and instinct in 

 neuter insects where use-inheritance is absolutely ex- 

 cluded ; and, lastly, the whole of the wonderful protective 

 and distributive contrivances of fruits and seeds, and the 

 still more wonderful and more complex adaptations of 

 flowers to insect fertilisation, this latter, be it remem- 

 bered, not under the pressure of an individual struggle for 

 life, but only for the purpose of obtaining an increase of 

 vigour and a somewhat more rapid multiplication, giving 



