Chap, ii.] OF THE PROCESSES OF ORGANIC CALORIFICATION. 451 



doubt.^ It is known besides that intellectual activity in a 

 healthy man and the cerebral sur-excitation in the lunatic are 

 accompanied by a sur-oxydation of the nervous substance, which 

 is betrayed by a greater production and excretion of phosphates. 

 Finally, it has been proved that the venous blood coming from 

 the brain, the blood of the jugular vein, had normally a higher 

 temperature than that of the carotid artery, and that cerebral 

 activity had as corollary a super-elevation of this venous tem- 

 perature. 



Professor SchifE has also, with the aid of thermo-electric 

 needles, seen the temperature rise in excited nervous cords, but 

 rise less in proportion as the animal was near death. 



All the anatomical elements, all the tissues, all the organs, 

 co-operate, then, in the production and maintenance of organic 

 heat, without which, on the other hand, they could not continue 

 to live; but in the vertebrates, and probably in the higher 

 invertebrates also, it is certainly the muscular system which 

 furnishes the most powerful calorific tribute. The muscles are, 

 in effect, the seat of veiy important nutritive exchanges, and 

 besides, in the mammifers, they represent about a third of the 

 weight of the body. 



Reaumur, Huber, Newport, &c., have seen the temperature 

 rise in a bocal containing insects, when these animals were put 

 in movement by disturbing them. Dufour has proved that 

 dm-ing the repose of the Sphinx apropos, the temperature of that 

 insect is only eight degrees above that of the ambient air, while, 

 at twilight, when the animal is in a state of activity and flies, 

 the difference may reach ten degrees. M. Maurice Girard has 

 seen the temperature of the Acheronlia atropos almost equal that 

 of warm-blooded animals after a prolonged flight. The ambient 

 air being at 23°,4, he has found in the abdomen of the sphinx 

 25°,5, and in the thorax 32, and even 37 degrees. 



' Pierquin, quoted by Gratiolet, Anatomie Oomparie du SysQme Nenieux 

 dans ses Supports amo V Intelligence. — Blumenbach, in Archives de MSdecine, 

 1861, t. I. 



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