246 ANIMAL HEAT. 



injury. Again, parts perfectly paralysed still maintain a temper- 

 ature above that of the surrounding medium, as well as circu- 

 lation, secretion, &c. e , and sometimes the same as in health. 



Dr. Philip considers galvanism an important agent in the 

 nervous system, and found that it raised the heat of fresh arterial 

 blood 3 or 4, and, at the same time, made the blood dark; 

 a circumstance proving that the action is purely chemical, an 

 alteration of some constituents of the blood to that state in which 

 their capacity for caloric is less. f 



There is certainly no more reason to believe animal heat de- 

 pendent on the nervous system, than secretion and every organic 

 function. That, like these, it is influenced by the state of the 

 nervous system, is certain; but never, I imagine, except through 

 the instrumentality of chemical changes. 



The purpose of animal heat is no doubt the performance of 

 the processes of the animated system, chemical, eleptrical, and 

 vital, which cannot continue unless at a certain temperature, nor 

 unless a certain degree of fluidity is preserved in some constitu- 

 ents of the system, and of solidity in others. 



e Dr. Philip, we have seen, found rabbits just killed cool in exactly the same 

 time, whether the brain and spinal marrow were destroyed or not, although when 

 these were destroyed a stop was put to the secretion of gastric juice. Yet when 

 the same was done to a living rabbit, with the same effect on the stomach, the 

 animal's temperature fell. This, however, would result from the shock given to 

 the nervous system as merely a part of the body, for the same happens every day 

 in cases of severe injuries even of the extremities. 



f Experimental Inquiry, p. 230. sqq. 



Vegetables and animals are prepared for almost all climates, and for temper- 

 atures higher than the heat of any country. Dr. Reeve found larvae in a spring at 

 208 ; Lord Bute, confervae and beetles in the boiling springs of Albano, that 

 died when plunged into cold water. A species of chara will flower and produce 

 seed in the hot springs of Iceland, which boil an egg in four minutes. ( Drs. Hodg- 

 kin and Fisher's translation of Dr. Edwards's work, p. 467., where will be found 

 many curious facts of this nature, though less striking. ) One plant, uredo nivalis, 

 which is a mere microscopic globule, is said to grow and flower under the snow. 



Some cold-blooded animals bear heat very badly. Dr. Edwards says that 

 frogs die in a few seconds in water at 107. (1. c. p. 40.) Yet a species of taenia 

 has been found alive in a boiled carp ; but then the carp which it inhabits will 

 live in water as hot as human blood. (Sennebier, Notes to his Translation of 

 Spallanzani.) 



