CONTROL OF BODY TEMPERATURE AND FEVER 747 



THE CONTROL OF TEMPERATURE 



In the case of man the body temperature is very largely under volun- 

 tary control, as by the choice of clothing and the artificial heating of the 

 room. Desirable as this voluntary control of heat loss may be, there can 

 be little doubt that it is often managed to the detriment of good health. 

 Living in overheated rooms during the cooler months of the year so 

 diminishes the loss of heat from the body that the tone and heat-produc- 

 ing powers of the muscular system are lowered. Not only does this 

 diminish the resistance to cold, but it causes the food' to be incompletely 

 metabolized so that it is stored away as fat. The superficial capillaries 

 also become constricted and the skin bloodless and " pasty." It is not 

 looks alone that suffer, however, but health as well, for by having so 

 little to do the heat-regulating mechanism gets, as it were, out of gear, 

 so that when it is required to act, as when the person goes outside to 

 the cold air, it may not do so as promptly as it should, with the result 

 that the body temperature falls somewhat and catarrh, etc., are the 

 result. There can be little doubt that much of the benefit of open-air 

 sleeping is owing to the constant stimulation of the metabolic processes 

 which it causes. 



As will be inferred from what has been said above, the control between 

 heat production and heat loss is effected through a nerve center located 

 in or near the corpora striata. In most animals, when the spinal cord 

 is cut in the cervical region, the body temperature quickly falls unless 

 artificially maintained. In the case of man, on the other hand, it has 

 usually been observed, after accidental section of the spinal cord in the 

 cervical region, that a rise in temperature occurs. In twenty-four un- 

 complicated cases of spinal-cord injury in man, collected from the rec- 

 ords of Guy's Hospital by Gardiner and Pembrey, it was found that 

 nineteen showed hyperthermia (sometimes amounting to 43.9 C.), and 

 only five, hypothermia (sometimes 27.6 C.). If the patient lived, the 

 ultimate effect of the section, as in the lower animals, would no doubt 

 be the loss of the power of maintaining a constant temperature. 



The extent to which the animal comes to behave as if cold-blooded, after 

 section of the spinal cord, varies considerably according to the level of 

 the lesion; if the cord is cut in the upper thoracic region, for example, 

 the regulation against cold, although distinctly less efficient than normal, 

 is far better than when the section is made through the cervical cord. 

 This difference is dependent on the fact that after the lower lesion much 

 larger muscular groups and skin areas are left intact, so as to make 

 regulation possible. Section of the dorsal cord in mice has been found 

 by Pembrey to abolish entirely the increased metabolism which occurs 

 in normal mice when they are exposed to cold. 



