76 VERTEBRATED ANIMALS. 



gentlemen touched any part near the seat of life, as the 

 tongue or side, it felt nearly as cold as a piece of ice 

 under ordinary circumstances. Thus though these per- 

 sons were in a temperature of 260, and even in some exper- 

 ments as high as 264, the heat of their bodies never rose 

 higher than 102 P making a difference of 160 between 

 them and the air in which they were placed. 



212. In what manner the heat is carried off". If we 

 look for the means which nature displays to carry aw r ay 

 the superabundant heat to which the system is exposed, 

 we shall find that perspiration is the most obvious, though 

 not the only one to which we can refer. The boiling 

 water in the rooms in which these experiments were 

 made, as is the case everywhere at the surface of the 

 earth, never exceeded 212 degrees, the remaining heat 

 being carried off by the steam rising from its surface. 

 In like manner the gentlemen state, that within a few 

 moments after entering the heated room, their persons 

 were covered with a profuse perspiration, which contin- 

 ued as long as they stayed. But beside this cause, the 

 operation of heated air on the system is not so great as 

 might be expected in consequence of its being so highly 

 rarified and expanded, that comparatively few particles 

 came in contact with the surface of the body. It has 

 been found also, that the quantity of oxygen consumed 

 by the lungs (which is' the source of animal heat), during 

 these experiments, is much less than ordinary, most proba- 

 bly owing to the rarity of the air. 



213. It appears that these are the several causes which 

 conspire to keep the temperature of the animal system 

 nearly the same as ordinary, when exposed to high de- 

 grees of heat. 



STRUCTURE OF THE BONY, OR OSSEOUS FABRIC. 



214. The framework of all vertebrated animals is made 

 of bone, the appearance of which we need not describe. 



What are the means employed by nature to resist high degrees of 

 heat? Why is the temperature of "boiling water stationary at 212 de- 

 grees? 



