416 TEMPERATURE AND LIFE. 



l)eratuie, local or general, according to the intensity and duiation of 

 the activity. It is tinis that a muscle in the act of contracting evolves 

 more heat than when in a state of repose, and this production is such 

 that it easily increases the temperature of tlio body 2^ 3^, 5"^. In 

 the same manner, a mental or intellectual etloit results in a produc- 

 tion of considerable heat. The glands iu an active state generate 

 large quantities of heat, as is seen by the temperature of their secre- 

 tions and of the venous blood, which has served in the formation of the 

 latter. This is why the venous blood of the kidneys is warmer than 

 the arterial blood, and according to Claude Bernard the temperature 

 of the hepatic vein, which brings back the blood from the liver to the 

 heart, is the highest in temperature, especially during the process of 

 digestion, at which time the liver is very active, and the chemical proc- 

 esses which take place are also numerous and intense. This is suffi- 

 cient to show the dependence of the generation of heat upon the chem- 

 ical activities of the body. 



By reason of natural and normal cessations of the phenomena which 

 are instrumental in generating and liberating heat, it is impossible for 

 the temperature of a being to be absolutely efjuable. Even with the 

 most warm-blooded animals there are many normal variations. In a 

 sound man, in normal condition, these variations take place within the 

 space of about 24 hours. The temperature is highest from 10 o'clock, 

 or midday, to G or 7 o'clock in the evening, reaching its lowest point 

 between midnight and G o'clock in the morning. Violent exercise, of 

 course, increases it several degrees, and the process of digestion is 

 accompanied by a slight fever. In a word, a multitude of circumstances 

 occur each hour which render variable, within certain limits, it is true, 

 the generation of heat. In addition, and this is quite natural, accord- 

 ing to the explanations givtn above, the temperature is not the same 

 in all portions of the organism. Certain portions are more thermogenic 

 than others, and others are more exi)Osed to a loss of heat. The calo- 

 rific topogra[)hy of the organism is accurately known. We know that 

 the hei)atic vein is one of the warmest points of the body, its position 

 being a i)rotected one, and containing, as it does, blood heated by the 

 intense chemical action which takes place in the liver. The brain has 

 probably the same temperature as this vein. On the other hand, the 

 skin always shows a much lower temperature (3°, 5°, or G°) than that 

 of the rest of the organism, suftering as it does considerable loss from 

 radiation. 



Leaving the question of external heat, we find that internal tempera- 

 ture is the direct result of two factors, thermic generation and waste. 

 Heat generated is the result of chemical processes, infinite in variety, 

 of which the body is the theatre, processes among which that of oxi- 

 dation holds a predominant place. As soon as oxidation is retarded, 

 there follows a didiculty in breathing, accompanied by a lowering of 

 the temperature. The cause of this is the diminution itself and the 



