26S THE EVOLUTION THEORY 



this may not have an effect on the germ-cells, and one which will 

 correspond to the changes induced on the body, so that if the poor 

 nutrition should last through many generations an hereditary de- 

 generation of the species would occur, which would not at once 

 disappear though the animals were transferred to more favourable 

 conditions. 



We certainly know nothing of how far the minuteness of the 

 determinants of the germ-plasm, the whole quantity of the germ- 

 plasm, or the reduced size of the germ -cell, may bear an internal 

 relation to the smallness of the animal which develops therefrom, 

 but it surely cannot be regarded as absurd to suppose that there is 

 some such relation. There are no experiments known to me which 

 prove that meagre diet brings about a progressive decrease in the 

 size of the body. Carl von Voit has observed that dogs of the same 

 litter grew to very different sizes of body according as they received 

 abundant or scanty food, but it would be difficult to make animals 

 small through scantiness of food and at the same time to keep them 

 capable of reproduction, and thus proofs of the inheritance of the 

 dwarfing are lacking. Moreover, the experiments which Nature 

 herself has made are never quite convincing, because we never can 

 definitely exclude the indirect effect of altered circumstances. The 

 case of the feral horses of the Falkland Islands, so often cited since 

 the time of Darwin, which have become small 'through the damp 

 climate and scanty food,' seems to me, of all known cases of the kind, the 

 one we should most readily attribute to the direct effect of continued 

 scanty diet; but even here we cannot altogether exclude the possibility 

 of the co-operation of adaptations of some kind to the very peculiar 

 conditions of life in these islands, as far as the feral horses are 

 oncerned. I have not been able to find any record of more modern 

 exact investigations either regarding these feral horses, or in regard 

 to the others which are reared in the Falklands under conditions of 

 domestication. Darwin himself, however, in the Journal of his famous 

 voyage tells us much that is interesting in regard to the mammals of 

 the Falkland Islands. Cattle and horses were brought there in 

 1764 by the French, and have increased greatly in numbers since 

 that time; they roam about wild in large herds, and the cattle are 

 strikingly large and strong, while the horses both wild and tame are 

 rather small, and have lost so much of their original strength that 

 they cannot be used for catching wild cattle with the lasso, and 

 horses have to be imported from La Plata for this purpose. From 

 this contrast between the horses and the cattle we may at least 

 conclude that it cannot be ' scantjr food ' alone which causes the 



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