MTIOLOG Y—PA THOLOGY 



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(especially in the old days of stocks), with a tight belt and knapsack 

 with cross-belts, and is at the same time marching in close formation 

 (when the air must certainly be impure from carbon dioxide and 

 dust) under a tropical sun, it is obvious that, especially if there is 

 a fairly high relative humidity in the atmosphere, he cannot get 

 rid of this heat, and there is bound to be either thermic fever or 

 heat syncope in a certain number of cases. 



Predisposing Causes. — Heat stroke is, if anything, more common 

 among children than adults, but it is very liable to be mistaken for 

 other diseases. It is more common among men than women, owing 

 to the greater exposure of the former. Among men it is principally 

 found in stokers and in soldiers during exhausting marches. Among 

 soldiers the classical instance often quoted is the account of the 

 march of the 43rd Regiment in the Indian Mutiny for over 1,100 

 miles, mostly across the plains of India, in the hottest weather. 



The men remained quite well for 969 miles, when they became 

 exhausted, and even emaciated; but in the narrow Kowri of the 

 Bisramgunge Ghat, when the temperature in the tents ranged 

 from 115° to 127° F. in the day, and on one occasion was 105° F. 

 at midnight, they suffered severely, and two officers and eleven men 

 died in four days, and later on seven more died in three days. 



There is no doubt that exhaustion and unsuitable clothing were 

 formerly the great causes of the frequency of attacks of heat stroke 

 in the army. In Chicago, in 1916, labourers formed 64-9 per cent, 

 of the cases, but the majority of them were also complicated with 

 alcoholism. 



Race appears to have a certain amount of effect, for it is more 

 common in Europeans than in negroes or East Indians, though 

 it is met with in all. In Chicago, in 1916, 79-8 per cent, of the 

 cases were in the third, fourth, and fifth decades, so that age may 

 also be a predisposing cause. Previous illness is a great predisposing 

 cause. Hot winds help to induce this condition ; in India the 

 hot wind ' loo marna ' is much dreaded by the natives. Of all 

 predisposing causes, alcohol is probably the most important. 



Pathology. — Marinesco has shown that a temperature of 47° C. is 

 immediately fatal to animals, while a temperature of 45° C. kills in 

 one hour, and one of 43° C. after a longer lapse of time, the essential 

 pathological change being chromatolysis in the nerve cells; therefore 

 high bodily temperature may cause acute serious nerve-cell changes. 



But the effect of high internal temperature has been further in- 

 vestigated by Halliburton and Mott, who have shown that a tem- 

 perature of 47° C. (117° F.) is the coagulation temperature of neuro- 

 globulin ; while Hewlett had previously shown that egg-white would 

 coagulate at a much lower temperature than usual if this is 

 maintained for some time. His experiments were repeated by 

 Halliburton and Mott on cat's brains, and they found that at 

 42° C. (108° F.) the neuroglobulin separated out, but not at lower 

 temperatures. Cat's brains kept at 42° to 43° C. for three and a 

 half hours showed chromatolysis in the nerve cells. They, there- 



