THE TEMPERATURE OF THE MONKEY AND ITS DIURNAL VARIATION. 99 



with regard to its mean temperature the monkey may be placed intermediate between 

 man and most of the higher mammals. 



Diurnal variation. — This is considerably greater than in man and many of the 

 lower animals. According to Jurgensen and Liebermeister (13), and many other 

 observers (14), the range in man is about 1° C, the maximum being reached between 



5 and 8 p.m. and the minimum between 3 and 6 a.m. In the lower animals few exact 

 observations have been made throughout the day and night. Bidder and Schmidt (15) 

 in a cat found a mean range for 11 days (24 hours) of I "3 — minimum 37 '8 between 



6 and 8 a.m., maximum 39'08 between 8 and 10 p.m. Strecker (16), Siedamgrotzky 

 (17), Hobday (18), and Liska (19) in horses, Hunter (20) in the ass, Robertson (21) 

 in oxen, Carter (22) in the rabbit, cat, and dog, Reichert (23) in the dog, and 

 Corin and Van Benedin (24) in pigeons, have all found evidence of a distinct 

 and fairly constant diurnal variation, which may be generally stated to be from 

 1° to 2° C. 



Hale White and Washbourn (8) in two healthy rhcesus monkeys found the range 

 to be about 3 "5° C. From observations on five healthy monkeys extending over a 

 period of 12 days (Period I.), we have found the mean diurnal variation to be 1'58, 

 ] '73, 1*84, 1'47, and I'll respectively, giving an average figure for the whole five of 

 1'62. The minimum was reached between 3 and 5 a.m., and the maximum between 

 5 and 7 p.m. The greatest range in any single day of 24 hours for any individual 

 monkey was 3 '4° (35 '8-39 "2), and the least 2° (36 '8- 38 '8). The range of the diurnal 

 temperature variation is therefore two or three times as great as in man. 



Effect on diurnal variation of changing the daily routine. — Several attempts have 

 been made to investigate the influence of the inversion of the daily routine in the 

 human subject. Debczynski (25) found in healthy individuals that : — 1. Muscular 

 exercise raised the body temperature in direct proportion to its intensity and duration 

 from 0'1° to 0*3° C. after ^ to 2 hours' work. 2. Muscular work carried on through the 

 night inverted the daily temperature curve, and gave the highest temperature in the 

 morning (37*8) and the lowest in the evening (35'3). 3. Night watching without 

 muscular work produced a similar inversion only with a smaller swing — 3 7 '7 in the 

 morning and 37 '5 in the evening. The original article is not obtainable by us, and in 

 the short abstract in the reference no details are given, and it is not stated how the 

 'temperature was taken. Krieger (26) has also shown that when an individual sleeps 

 during the day and works during the night his temperature curve is inverted. 

 Buchser (27), an engineer who was accustomed to sleep through the day and to work 

 at night, found that his morning temperature oscillated between 37 and 37 '5, 

 while the evening record was between 36*6 and 37, averaging 36"8. Jaeger (28) 

 i made an extended series of observations on five young men (military bakers) whose 

 daily routine was as follows : — They worked from 3 a.m. to 4 p.m. in a heated room ; 

 they rested from 4 to 7 p.m. ; from 7 to 8 p.m. they had light work, and from 8 p.m. 

 to 3 a.m. they slept. Jaeger concluded from these observations that night work and 





