596 A MANUAL OF PHYSIOLOGY 



store of hepatic glycogen. Certain investigators have found that 

 after an adequate dose of curara no puncture fever can be obtained, 

 and they locate the increased metabolism associated with the fever 

 in the muscles. Others maintain that even after curara the puncture 

 is followed by fever, but is not followed by fever if strychnine has 

 first been given. They accordingly conclude that the rapid com- 

 bustion of the glycogen (or the dextrose derived from it) is the 

 primary factor in the increased metabolism. It may be pointed out, 

 however, that neither experiment is a crucial test. For if strychnine 

 reduces the liver glycogen, it also reduces the glycogen of the muscles. 

 And if in the puncture fever the liver glycogen is transformed into 

 dextrose more rapidly than usual, the dextrose is probably in great 

 part used up in the muscles more rapidly than usual, else it would 

 appear in the urine. The effect of strychnine on the puncture fever, 

 then, is no proof that the muscles are not essentially concerned in it. 

 On the other hand, the alleged absence of the fever after curara is 

 not sufficient to show that the muscles are alone concerned. For 

 curara causes a lowering of the body -temperature, which, if it be 

 not overcompensated, may mask the fever. The positive result 

 of the puncture in curarized animals, which some observers say they 

 have obtained, would, if confirmed, be important evidence that the 

 primary effect is not on the muscles, or, at least, not solely on them, 

 but would not prove that it is on the liver. That the liver is con- 

 cerned, however, is more directly indicated by the fact that during 

 the puncture fever the liver continues to be what it is under normal 

 conditions, the warmest organ in the body, warmer than the blood 

 in the root of the aorta by about i C. The most probable conclusion 

 is that the increased production of heat in this form of experimental 

 fever is due to an increased metabolism of carbo-hydrate (glycogen) 

 both in the liver and in the muscles. 



Injury to various portions of the cortex cerebri in the dog and 

 other animals, and lesions of the pons, medulla oblongata and cord 

 in man may also be followed by increase of temperature. When the 

 spinal cord is cut below the 'level of the vaso-motor centre, the 

 increased loss of heat from the skin due to dilatation of the cutaneous 

 vessels masks any increase of the heat-production which may 

 possibly have taken place, and the internal temperature falls ; but 

 if the loss of heat is diminished by wrapping the animal in cotton- 

 wool the temperature may rise. From such phenomena it has been 

 surmised that certain ' centres ' in the brain have to do with the 

 regulation of temperature by controlling the metabolism of the 

 tissues ; that they cause increased metabolism when the internal 

 temperature threatens to sink, diminished metabolism when it 

 tends to rise. The cutting off, it is said, of the influence of the 

 ' heat centres ' by section of the paths leading from them allows the 

 metabolism of the tissues to run riot, and the temperature to increase. 



The behaviour of hibernating mammals, such as thfe marmot, 

 dormouse, hedgehog, and bat, is of interest in connection with 

 the temperature regulation. In the active waking state these 

 animals are homoiothermal, but in profound winter sleep they 

 are poikilothermal, the body-temperature rising and falling 

 with that of the air. The rectal temperature may be as low as 

 2 C. There is an intermediate state in which the animal is 

 partially awake, though inactive, and its temperature is much 



