226 LOWER ANIMALS. 



and lives to ten or fifteen, and sometimes to over twenty, and one 

 has been known to live to thirty-four. Owing to the conditions 

 under which the dog is kept, he does not usually breed before 3 or 4 

 years old, and his average age of reproduction must be about 7 or 

 8 years. His association with man and the instruction given him 

 when young, makes him mentally more active than the horse. 



The sheep, an animal slightly larger than the average dog, be- 

 gins to breed at less than one year of age and, according to Youatt, 

 will continue to breed up to the age of ten. The average age of 

 reproduction is about 3 or 4 years, and the intelligence is corre- 

 spondingly less than that of the dog. 



RABBITS AND SQUIRRELS. 



The rabbit breeds early and often. It begins at the age of six 

 months, and, in a state of nature, can rarely survive to the age of 

 three. The average age of reproduction must be less than two 

 years. 



The squirrel, an animal somewhat smaller than the rabbit but 

 vastly more intelligent, breeds only once a year, and the young 

 remain with the parents until the next spring. I have not been 

 able to determine whether they breed at one year of age, or wait 

 until the second year. In either case, the average age of reproduc- 

 tion must be greater than with the rabbits, as they produce few 

 at a time and live longer. "It may be considered pretty certain 

 that both the Ground Squirrel and the Flying Squirrel hibernate, 

 and these are certainly among the lowest — perhaps are actually the 

 lowest — in intelligence of the whole tribe." 14 Hibernation may be 

 considered as so much time taken out of the life of the individual 

 which hibernates. 



(14) Mills, Animal Intelligence, p. 59. 



