DEVELOPMENT OF HEAT. 583 



their Calorifying power upon the due supply of material for the Chemical 

 changes which generate Heat, has lately received some very remarkable 

 additions from the experiments of M. Chossat.* He found that Birds, when 

 totally deprived of food and drink, suffered a progressive, though slight, daily 

 diminution of temperature. This diminution was not so much shown by a 

 fall of their maximum heat, as by an increase in the diurnal variation, which 

 he ascertained to occur even in the normal state. The amount of this varia- 

 tion, in Birds properly supplied with food, is about 1^ Fahr. daily; the 

 maximum being about noon, and the minimum at midnight. In the inaniti- 

 ated state, however, the average variation was about 6, gradually increasing 

 as the animal became weaker: moreover, the gradual rise of temperature, 

 which should have taken place between midnight and noon, was retarded ; 

 whilst the fall subsequently to noon commenced much earlier than in the 

 healthy state : so that the average of the whole day was lowered by about 4^ 

 between the first, and the penultimate days of this condition. On the last day, 

 the production of Heat diminished very rapidly, and the thermometer fell from 

 hour to hour, until death supervened ; the whole loss on that day being about 

 25 Fahr., making the total depression about 295. This depression appears, 

 from the considerations to be presently stated, to be the immediate cause of 

 Death. On examining the amount of loss sustained by the different organs of 

 the body, it was found that 93 per cent, of the Fat had disappeared,- all, in 

 fact, which could be removed ; whilst the Nervous Centres scarcely exhibited 

 any diminution in weight. The loss of weight of the whole body averaged 

 about 40 per cent. ; and that of the various other component tissues was very 

 much what might have been anticipated. From the constant coincidence 

 between the entire consumption of the Fat, and the depression of Tempera- 

 ture, joined to the fact that the duration of life under the inanitiating process 

 evidently varied (other things being equal) with the amount of Fat previously 

 accumulated in the body, the inference seems irresistible, that the Calorify- 

 ing power depended chiefly, if not entirely, on the materials supplied by this 

 substance. The maintenance of the normal amount of matter in the Nervous 

 centres is a very remarkable fact ; and seems to countenance the idea formerly 

 suggested, that the substances peculiar to Nervous tissue may be formed from 

 Fatty matter rather than from a Protein-compound ( 77). Whenever, there- 

 fore, the store of combustible matter in the system was exhausted, whether 

 by the Respiratory process alone, or by this in conjunction with the conversion 

 of Adipose matter into the materials for the Nervous or other tissues, the 

 inanitiated animals died, by the cooling of their bodies consequent upon the 

 loss of Calorifying power. That this is the real explanation of the fact, is 

 shown by the results of a series of very remarkable experiments performed by 

 M. Chossat, with a view of testing the correctness of this view. When inani- 

 tiated animals, whose death seemed impending, (in several instances death 

 actually took place, whilst the preliminary processes of weighing, the applica- 

 tion of the thermometer, &c., were being performed,) were subjected to artifi- 

 cial heat, they were almost uniformly restored from a state of insensibility and 

 want of muscular power to a condition of comparative activity ; their tempera- 

 ture rose, their muscular power returned, they flew about the room and took 

 food when it was presented to them ; and, if the artificial assistance was suffi- 

 ciently prolonged, and they were not again subjected to the starving process, 

 most of them recovered, 'if they were left to themselves too early, however, 

 the digestive process was not performed, and they ultimately died. Up to the 

 time when they began to take food, their weight continued to diminish ; the 



* Rec.herches Experimentales sur 1'Inanition, Paris, 1843. See, also, the Brit, and For. 

 Med. Rev. for April, 1>44. 



