NER VO US CONTR OL OF TEMPERA TURE. 857 



mass, and thus the loss of heat due to vasomotor paralysis is less serious 

 than in a small animal. Animals also differ in their method of 

 regulation ; some, as in the case of man, have a well-developed vaso- 

 motor system for the cutaneous surface, which is so slightly protected by 

 natural covering ; others, as in the case of dogs, have a thick fur, and 

 regulate their temperature chiefly by variations in the production of 

 heat and in the loss of heat from the respiratory tract. The distribu- 

 tion and part played by the sweat glands varies greatly, as shown by a 

 comparison of men and horses with dogs and cats. It is to be noticed 

 further, in this respect, that marked differences exist even in individuals 

 of the same race and variety ; thus, some men and horses sweat much 

 more readily and profusely than others. 



In addition to the above factors, it is necessary to consider the 

 external conditions under which the injured animal finds itself. The 

 external temperature greatly modifies the part played by the loss of heat 

 from the paralysed parts. Most animals adopt a different posture, 

 according to their need of heat or cold ; thus a heated dog, rabbit, or 

 mouse lies with extended trunk and limbs, whereas the same animal 

 when it is cold, coils or huddles itself together. It is almost unneces- 

 sary to point out that a paralysed animal could not assume these 

 instinctive postures. A normal rabbit tied down in an extended position 

 loses an abnormal quantity of heat, and its temperature falls, and in 

 some cases the body is so greatly cooled that death results. 1 



The above facts must therefore be borne in mind during any ex- 

 amination of the effects of section or injury of the spinal cord. 



Attention was first drawn to the influence of the nervous system upon 

 temperature, by the experiments and clinical observations of Benjamin 

 Brodie. 2 He found that, after the head of an animal was cut off, or the 

 cord divided high up in the cervical region, the circulation of the blood 

 still continued when artificial respiration was performed, but the tem- 

 perature fell even more quickly than in a dead animal. This Brodie 

 correctly attributed to the great loss of heat from the circulating blood, for 

 if the circulation was stopped by ligature of the heart, the fall of tem- 

 perature was much retarded. It was also found that woorara (curari) and 

 essential oil of almonds, by suspending the action of the central nervous 

 system, also caused a fall in temperature. Brodie further compared the 

 discharge of carbon dioxide by normal rabbits with that of rabbits with 

 the brain removed or poisoned by woorara or the essential oil of almonds ; 

 he states that the same quantity of carbon dioxide is formed in each of 

 these cases, and therefore that the heat production is not due to chemical 

 change but to nervous action. This conclusion is not warranted by the 

 results of the determinations of the respiratory exchange, and the 

 results themselves are not comparable, for, even when it was possible, the 

 experiments were not made upon the same animals. 



The work of Brodie led to numerous experiments and discussions on 

 this subject by Chossat, 3 Hale, 4 Legallois, 6 Wilson Philip, 6 Hastings, 7 



1 Legallois, Ann. de chim. etphys., Paris, 1817, Sr. 2, tome iv. p. 21. 



2 Phil. Trans., London, 1811, vol. ci. p. 36 ; 1812, vol. cii. p. 378 ; Med.-Chir. Trans., 

 London, 1837, vol. xx. p. 146. 



3 Deutsches Arch. f. d. PhysioL, Halle, 1822, Bd. vii. S. 282. 



4 London Med. and Phys. Journ., vol. xxii. 



5 Ann. de chim. ctphys., Paris, 1817, Ser. 2, tome iv. 



6 "Experimental Inquiry into the Laws of the Vital Functions," London, 1818, 2nd 

 edition, p. 197 et seq. 



7 Quart. Journ. Sc. Lit. and Arts, London, 1823, vol. xiv. p. 96. 



