A STUDY IN MORBID AND NORMAL PHYSIOLOGY. H'i 



For reasons just assigned it seems to me that there is no inherent absurdity in 

 the inhibitory lieat centre theory. Its correctness is however certainly not proven 

 by any facts as yet adduced. It is probable that the bulk, at least, of the animal heat 

 is developed in the muscles, and it is possible that the so-called general vaso-motor 

 centre of the medulla is only the centre of the abdominal circulation. As is well 

 known, the bloodvessels of the abdomen, if perfectly relaxed, arc snfHcient to hold 

 almost all the blood of the body. It is conceivable then that they may dominate 

 the arterial pressure ; so that a vaso-motor centre for the muscular system may exist 

 higher up in the brain than the medulla, and yet not reveal itself by changes in 

 the arterial pressure, just as the addition of a hundred men to an army of 100, ()()(), 

 or of a gill of water to a hogshead fidl would not lie noticed. If such a muscular 

 centre did exist, section of the medulla at the junction with the pons would quicken 

 the muscular circulation most markedly and might thereby materially increase the 

 amount of heat production. 



The determination of the comparative probability of the two theories must be 

 left to a later portion of this paper, after it has been shown that there are high up 

 in the brain certain centres evidently connected in some way with the production 

 of animal heat. 



For the present we can only conclude that the rise of bodily temperature follow- 

 ing separation of the pons from the cord is due either to paralysis of an inhibitory 

 heat centre or of a muscular vaso-motor centre. 



Although the higher centre, whatever its nature may be, which dominates animal 

 heat production is very powerful, it is evident that the thermic activities of the 

 organism must be very greatly aficcted by the circulation and the respiration : 

 that cutting off the materials of growth and the oxygen required for the life 

 processes must exercise a dominant influence, and that an increased supply of these 

 agents must also produce a decisive effect. The following experiment is of interest 

 as showing the very great power of defective respiration in preventing the increased 

 heat production which otherwise would have followed the operation performed. 



Experiment G3. 



A dog Weight about 30 lbs 



Air Tfre Boi Rkct. Qbnkral Sample Aiu ^^.'"f^rM rAl;c^cK 



Tkmi>. Tkmp. TbiMP. Tkmp. Meter. Meter. Meter. <- 4'^^^" Tube 



(Fah.) (Fah.) (Fah.) (Fah.) (cub. ft.) (cub. ft.) (cub. ft.) (cub. ft.) (cub ft.) 



12:16 p.m. 800.88 bP.GS 790.8 102O.2 925.44 21.21835 02.9418 133.90C2 12b.23 



12:31 80..5 81.9 



^l:f 81.22 82.04 80.52 102.2 995.218 21.2495 02.98C8 133.93275 126.2.505 



80.86 81.91 0.72 C9.778 0.03115 0.045 0.02655 0.0205 



(mean) 80.86 (gain) 0.03115 



li)5 09.80915 



(gain) 



l:45r.M._Section made. Respiration at once ceased. Artifici:.! respiration was kept up 

 about half an hour, when imperfect respiration came on. From the beginning the temperature of the 

 rectum rose slowly and steadily. At 3 v. m. respiration very slow, only four a minute; lips, etc., 

 cyanotic. Rectal temperature 106°. 7 F. 



