IN THE LOWER ANIMALS, ETC. 355 



variety in diet. In the warmer latitudes, he can 

 maintain a healthy existence on rice, fruits, or 

 roots ; but in the Arctic regions he can live exclu- 

 sively on animal food, and that of the most 

 oleaginous kind ; thus supporting vital combus- 

 tion in the respiratory process, and maintaining 

 the temperature of the body amidst the most in- 

 tense cold. 



I was informed by Dr. Walker, the able natural- 

 ist and surgeon of Lady Franklin's expedition, 

 that as he approached the colder latitudes on the 

 outward voyage, he felt obliged to live almost 

 entirely on animal food ; as the temperature dimi- 

 nished, he was compelled to select the fat portions 

 exclusively ; until, when within the Arctic circle, 

 he could subsist on blubber, finding it necessary 

 for the supply of an adequate amount of animal 

 heat. 



Having examined a large number of skulls of 

 various animals while engaged in preparing this 

 paper, I embraced the opportunity of ascertaining 

 to what extent disease occurred in their teeth. 

 I found several examples of injury arising from 

 mechanical causes, as in the case of teeth splin- 

 tered by shot, or the canines of the Carnivora 

 fractured by the animal's violent use of them, and 

 in other instances severe alveolar abscess conse- 

 quent upon the dislocation of otherwise sound 

 teeth. So far, however, as my own observation 

 extended, I could not find a single instance of 



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