CHAPTER XIV. 



LOWER ANIMALS. 



Tracing the effect of age of parent before reproduction, in the 

 development of mental ability, need not be confined to man. The 

 same result may be shown in the whole animal kingdom from the 

 highest to the lowest. It is my purpose, in the present chapter, 

 to compare various animals with each other very much as I have 

 compared the different races of men. In doing this I am somewhat 

 hampered by the want of accurate data, but I have been able to se- 

 cure enough to give a fair idea of the operation of the law of use- 

 inheritance. In making comparisons involving the ages of parents, 

 due consideration must be given to the size and bulk of the animals, 

 the degree of their activity, and the conditions under which they 

 exist. Thus, a comparison between a mouse and a tortoise for 

 age would not be legitimate unless due consideration be given to 

 their relative sizes and their relative degrees of activity. It is 

 also quite evident that a cow, which has little to do but eat, sleep 

 and reproduce, lives under quite different conditions from a deer, 

 which has to seek its food and keep on the alert against enemies. 

 For these reasons I have restricted my comparisons as much as 

 possible to animals of the same size, and have noted the other 

 differences so that the effect of age before reproduction may re- 

 ceive its proper consideration. 



THE APES. 



Next to man, the anthropoid apes are the highest of all animals. 

 Of the gorilla I have not been able to learn at what age he arrives 



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