PRINCIPLES OF VETERINARY SURGERY 53 



lungs ; and by evaporation. The maintenance of an equal 

 temperature under all circumstances in health, must there- 

 fore depend not only upon the production of a given amount 

 of heat, but also upon its continuous loss. If the production 

 exceeds the loss the temperature will immediately rise, but 

 if the reverse occurs the body temperature will fall below 

 normal. There being an internal furnace and an external 

 refrigerator, the mechanism maintaining the equilibrium 

 would appear to depend simply upon the cooling of the blood 

 brought to the surface, the amount being regulated by the 

 vaso-motor nerves. But this explanation is not entirely cor- 

 rect because the evolution of heat in any given muscle does 

 not vary in obedience to the amount of blood flowing 

 through it, which fact, being amply proven, demonstrates 

 that heat generation is augmented and depressed under the 

 direction of cerebro-spinal nerves that have no influence 

 upon the blood vessels. 



Whether or not there is a thermic center in the brain 

 that presides over the heating apparatus of the body, does 

 not specially interest the pathologist, who will be content to 

 know that heat (fever) is governed by the nervous system, 

 independently of its influence on the arteries, as well as by 

 external exposure of the blood and evaporation. 



Whether fever is due more to the repressed dissipation 

 than the increased production, is a question that naturally 

 arises in the study of its etiology. Fever might easily be ex- 

 plained by the ansemic condition of the. periphery during the 

 the first stage of diseases. It would be only logical to con- 

 clude that the lack of blood coming to the surface to be 

 cooled would produce increased internal heat, but experi- 

 ments have shown that depressed dissipation is not the sole 

 cause, but that there is also a marked increased generation. 

 Proof of this is shown by the rise of fever in a perspiring 

 animal, and also by the fact that a feverish animal will heat 



