CHAP. XXX.] THEORY OF ANIMAL HEAT. 425 



inefficient supply of oxygen, and the suspension of secretion and 

 the absence of symptoms characteristic of the accumulation of 

 excretory products in the organism, show that the chemical changes 

 accompanying the disintegration of the tissues are only taking 

 place in a slight degree, or are altogether suspended, the tempera- 

 ture often falls to 70, or even much lower. It is curious that, in 

 many of these conditions, the temperature should rise very rapidly 

 immediately after death. The most striking examples of this have 

 been placed on record by Dr. B. Dowler, of New Orleans, and 

 occurred in cases of yellow fever, etc. In one instance, just before 

 death, the temperature was 104 ; and, fifteen minutes after death, 

 it had risen to 113 in an incision in the thigh. The temperature 

 still remained very high for several hours after death. 



Hybernation. The phenomena of hybernation are dependent 

 upon the conditions we have just alluded to. Previous to becoming 

 torpid, the animal accumulates a quantity of fat, which is, as it 

 were, laid up as in a storehouse, to be consumed slowly, while the 

 period of annual sleep lasts. At this time, the activity of the vital 

 functions is much reduced, the animal lies perfectly still, the fre- 

 quency of the heart's action and of the respirations diminishes ; its 

 temperature falls many degrees, and it is placed in a condition the 

 most favourable for supporting life for a considerable period of time 

 with a very small supply of combustible material. The moment 

 the animal is roused, the vital processes again become active, and a 

 supply of food soon becomes necessary. In the case of the marmot, 

 in which animal the hybernation is complete, the pulse falls to 

 about 15 beats in a minute, and the respirations to 14 in an hour, 

 while in the waking state these are respectively 150 and 500. The 

 temperature of the body, during the hybernating period, may fall 

 as low as 35. If, however, the animal be exposed to warmth, the 

 frequency of the pulse and respiration increases, a much larger 

 quantity of oxygen is consumed, and a corresponding proportion 

 of carbonic acid exhaled. The temperature of the body suddenly 

 rises, and the animal soon dies, unless supplied with food. 



Theory of Animal Heat. It has been shown, that in certain parts 

 of plants, and in cold as well as warm-blooded animals, heat is de- 

 veloped coincidently with the consumption of oxygen, the com- 

 bustion of carbon, and the formation of carbonic acid. The heat 

 produced, and the chemical product of combustion, have been 

 observed to bear a certain general correspondence one with the 

 other. 



To understand the real nature of the development of heat in 



VOL. II. F F 



