ii THE THEEMIC ECONOMY OF THE OEGANISM 67 



hepatic vein is the warmest (39 '7) ; next comes that of the right 

 side of the heart (38'8), and then that of the left side of the 

 heart. These differences are not due only to the heating of the 

 air inspired and the evaporation of water in the lungs, since 

 according to Heidenhain and Korner results differing but 

 slightly are obtained when artificial respiration is practised with 

 air saturated with moisture and heated to 35 - 40. They came 

 to the conclusion that the higher temperature of the right side of 

 the heart, compared to that of the left, is mainly due to the heat 

 transmitted to the right heart by the venous blood coming from 

 the liver. 



In addition to the local differences of temperature it is interest- 

 ing to study more closely the normal variations of the temperature 

 of man in the course of twenty-four hours ; for differences are found 

 even when the temperature of the same part of the body (the rectum 

 or the arm-pit) is taken. These variations take a regular course 

 which has been the subject of many researches, the temperature 

 being methodically tested at every hour of the day and night. 



As early as 1843 Chossat, when studying the phenomena of 

 inanition in pigeons, noticed that on a regular diet the difference 

 in the temperature of these birds during the day and the night 

 averaged 0'74 (42'22 at noon, 41/48 at midnight), and that this 

 difference steadily increased during inanition, becoming 2*3 in the 

 first stage, 3'2 in the second, and 4'1 in the third, the one 

 immediately preceding death. He saw that this steady increase 

 of the difference between day and night temperatures during 

 inanition was due to an abnormal lowering of the night tempera- 

 ture, the temperature of the body remaining almost unchanged 

 during the day. 



In 1845 the daily variations of temperature were tested by 

 J. Davy, and later by a large number of investigators, among 

 them being Jiirgensen (1873), Liebermeister (1875), Einger and 

 Stuart (1877), Eichet (1889), Benedict and Snell (1902-1904). 

 The results obtained agree in the main and only differ in details 

 of secondary importance, which may be accounted for by differences 

 peculiar to the different subjects and the conditions under which 

 the observations were made. The normal curve of the variations 

 in temperature in the course of twenty -four hours given by 

 Jiirgensen shows a very regular course, as will be seen in Fig. 12, A, 

 reaching its minimum between 4 and 6 in the morning and its 

 maximum between 4 and 6 in the afternoon. During the day the 

 subject remained at rest in bed and took his usual food. The 

 curve Fig. 12, B, was obtained in the same person when fasting ; it 

 differs but little from curve A. The range is 0'8 in the case of 

 A, and 0'6 in B. When the subjects do not remain in bed during 

 the day, and do not perform any real muscular work, the difference 

 between the minimum temperature of the night and the maximum 



