752 METABOLISM 



tributed to a deficiency of salt in the food, for it sets in before the diet 

 has been curtailed and, when salt is given to a febrile patient, it is re- 

 tained in the body to a greater degree than is the case in the normal 

 individual. For some reason the tissues in fever have acquired the 

 property of retaining large quantities of salt. 



Attempts to study the water balance during fever have frequently been 

 made, but the technical difficulties of such investigations make the re- 

 sults uncertain and of little value. That some retention of water occurs 

 during fever is, however, evidenced by the dilution of the blood. At the 

 crisis this hydremia quickly disappears at the same time as the increased 

 elimination of chlorides is going on. Chlorides and water would there- 

 fore seem to behave in a similar fashion during fever. 



The Heat-regulating Center 



In all discussions on the regulation of body temperature and the 

 causes of fever, it is assumed that a heat-regulating or thermogenic 

 center exists somewhere in the brain. It is believed to be located 

 about the optic thalami or corpora striata, for it has been found in 

 rabbits that destruction of the brain anterior to this region does not 

 cause any change in body temperature, whereas destruction behind it 

 is followed by an entire upset in the heat-regulating mechanism. Fur- 

 thermore, artificial puncture of this part of the brain causes marked 

 elevation in body temperature in rabbits (heat puncture). Most in- 

 teresting experiments have been recorded by Barbour, 56 who succeeded 

 in applying heat or cold locally in the region of the centers. By the 

 application of cold, increased muscular metabolism, on the one hand, 

 and diminished heat loss, on the other, were excited; and conversely, 

 when warmth was applied, an increased heat loss and a diminished heat 

 production were observed. Irritation of this region of the brain in man, 

 as after cerebral hemorrhage, is also accompanied by remarkable dis- 

 turbances in heat regulation. It is believed by many that the essential 

 cause of fever in infective conditions, is an action on these centers by toxic 

 substances which develop in the blood. 



The centers may also be acted on by various drugs, some of w r hich 

 excite them to increase the body temperature, others, to lower the tem- 

 perature when this has already been elevated. When solutions of sodium 

 chloride are injected intravenously or subcutaneously or even sometimes, 

 particularly in children, when administered by mouth, more or less fever 

 may result. This must be a specific action of the Na ion, for, if instead 

 of pure solutions of NaCl. solutions containing calcium and potassium 

 salts as well as those of sodium are injected, no fever is induced. This 

 fact, taken along- with the close similarity between puncture diabetes 



