42 Veterinary Medicine. 



dioxide) and rapid breathing (which fails to secure its elimina- 

 tion), the over-driven animal soon perishes from asphyxia. Un- 

 der a high temperature of the external air, this condition is aggra- 

 vated since the rarified air contains just so much the less oxygen, 

 the absorption of which is the measure of the exhalation of car- 

 bon dioxide. 



Dr. H. C. Wood, who has experimented largely on the subject 

 in animals, finds the cause of heart failure in the coagulation of 

 the myosin, which takes place under ordinary circumstances at 

 115° F., but at a much lower temperature when a muscle has been 

 in great activity immediately before death. As the temperature 

 of thermic fever frequently reaches 113°, or even higher, he easily 

 accounts for the sudden syncope occurring during active, work in 

 a high temperature. As an example of such sudden rigor, he ad- 

 duces the sudden stiffening of the bodies of some soldiers killed 

 in battle during hot weather. 



Wood further shows that all the symptoms of thermic fever can 

 be produced in the rabbit by concentrating the temperature on its 

 head, which seems to imply a direct action on the brain and in par- 

 ticular on the heat producing and vaso-motor centres. This becomes 

 the more reasonable that the temperature attained does not im- 

 pair the vitality of the blood but, leaves the leucocytes possessed 

 of their amoeboid motion. He found, moreover, that if the heat 

 were withdrawn before it has produced permanent injury to the 

 nervous system, blood or other tissues, the convulsions and un- 

 consciousness are immediately relieved and the animal recovers. 



Other conditions may be adduced as predisposing or concurrent 

 causes of thermic fever. Whatever impairs the animal vigor has 

 this effect. Fatigue, as already noticed, is a potent factor, in 

 man a drinking habit ; in all animals a long persistence of the 

 heat during the night as well as the day ; impure air in badly 

 ventilated buildings ; and mechanical restriction on the freedom 

 of breathing. In military barracks with the daily temperature at 

 118° F. and the night temperature 105, the mortality became ex- 

 treme, and in close city car stables the proportion of sun-strokes is 

 enhanced. In all such cases, the air becomes necessarily more 

 and more impure continually. The atmosphere has the same 

 heat as the animal body, so that no upward current from the lat- 

 ter can be established, to create a diffusion. The carbon dioxide 



