328 REGULATION OF THE TEMPERATURE. 



The peripheral parte of the body exhibit more or less regular variations of their temperature 

 In the Pabi of the hand, the progress of events is the following :-After a relatively high night 

 temperature there is a rapid fall at 6 A.M which reaches its minimum ^ to lOj^ This 

 followed by a slow rise, which reaches a high maximum after dinner; it falls between 1 to 3 

 v v and after two or three hours reaches a minimum. It rises from 6 to 8 p.m., and falls 

 *gain towards morning. A rapid fall of the temperature in a peripheral part corresponds to a 

 rise of temperature in internal parts. 



(5) Many operations upon the body affect the temperature. After haemorrhage 

 the temperature falls at first, but it rises again several tenths of a degree, and is 

 usually accompanied by a shiver or slight rigor; several days thereafter it falls to 

 normal, and may even fall somewhat below it. The sudden loss of a large amount 

 of blood causes a fall of the temperature of Q J to 2 C. Very long-continued 

 haemorrhage (dog) causes it to fall to 31 or 29 C. 



This is obviously due to the diminution of the processes of oxidation in the amemic body, 

 and to the enfeebled circulation. Similar conditions causing diminished metabolism effect the 

 same result. Continued stimulation of the peripheral end of the vagus, so that the hearts 

 action is enormously slowed, diminishes the temperature several degrees in rabbits (Lcmdois 

 mid Amnion). 



The transfusion of a considerable quantity of blood raises the temperature 

 about half an hour after the operation. This gradually passes into a febrile attack, 

 which disappears within several hours. When blood is transfused from an artery 

 to a vein of the same animal, a similar result occurs ( 102). 



(6) Many poisons diminish the temperature, e.g., chloroform and the anaesthetics, 

 alcohol ( 23")), digitalis, quinine, aconitin, muscarin. These appear to act partly 

 by rendering the tissues less liable to undergo molecular transformations for the pro- 

 duction of heat. In the case of the anaesthetics, this effect perhaps occurs, and is 

 due possibly to a semi-coagulation of the nervous substance (?). They may also 

 act partly by influencing the giving off of heat ( 214, II.). Other poisons 

 increase the temperature for opposite reasons. 



The temperature is increased by strychnin, nicotin, picrotoxin, veratrin, laudanin. 



(7) Various diseases diminish the temperature, which may be due either to lessened produc- 

 tion of heat (diminution of the metabolism), or to increased expenditure of heat. Loewenhardt 

 found that in paralytics and in insane persons, several weeks before their death, the rectal 

 temperature was 30 to 31 C, in diabetes 30 C. or less ; the lowest temperature observed and 

 life retained, in a drunk person was 24 C. 



The temperature is increased in fever, and the highest point reached just before death, and 

 recorded by Wnndcrlich, was 44*65 C. (compare 220). 



214. REGULATION OF THE TEMPERATURE. As the bodily temperature 

 of man and similar animals is nearly constant, notwithstanding great variations in 

 the temperature of their surroundings, it is clear that some mechanism must exist 

 in the body, whereby the heat economy is constantly regulated. This may be 

 brought about in two ways ; either by controlling the transformation of potential 

 energy into heat, or by affecting the amount of heat given off according to the 

 amount produced, or to the action of external agencies. 



[The constancy or thermostatic condition of the temperature is brought about by 

 three co-operant factors, the thermogenic or heat-producing, the thermolytic or 

 heat-discharging, and the thermotaxic or mechanism by which heat-production and 

 heat-loss are balanced, and it is obvious that the last must be in relation with the 

 other two. The thermotaxic mechanism is developed last, is least pronounced in the 

 lower vertebrata, and is most easily liable to fail under injury or disease (Mac- 

 Alister).'] 



I. Regulatory Arrangements governing the Production of Heat. Lieber- 

 meister estimated the amount of heat produced by a healthy man at 1 -8 calorie per 

 minute. It is highly probable that, within the body, there exist mechanisms 

 which determine the molecular transformations, upon which the evolution of heat 

 depends. This is accomplished chiefly in a reflex manner. The peripheral ends of 



