INFLUENCE OF AGE. 803 



for muscular work. 1 Daily variations in the output of carbon dioxide 

 and in the intake of oxygen have been observed by Prout, Pettenkofer 

 and Voit, Fredericq, 2 and others ; these variations in metabolism more 

 or less correspond with those observed in the temperature, and will be 

 found discussed more fully in another part of this work. 3 



Best in bed throughout the day does not abolish the daily variation ; 

 it is still present, although modified, in cases of disease, attended or 

 unattended by fever ; the morning rise still takes place even when light 

 is excluded (Ogle). 



In animals, daily variations in temperature have also been observed, 

 but upon this point there are few exact observations taken throughout 

 the day and night. Strecker, 4 from observations upon 150 horses, found 

 the average temperature between 6.30 A.M. and 8 A.M. to be 37'9, that 

 between 5 P.M. and 6.30 P.M. to be 37'93 ; but the minimum was 37'2 

 and the maximum 38'6. In the case of oxen, Robertson 5 found the 

 average morning temperature 38 0- 7, the evening temperature 38 0> 9 ; in 

 the cat the minimum is 37'8 at 7 A.M. and the maximum 39*08 at 

 10 P.M. (Bidder and Schmidt). 6 Hunter states that the temperature of 

 an ass was 0'5 higher in the evening than in the morning. According 

 to the observations of Siedamgrotzky, 7 the maximal daily temperature in 

 horses was 38'2 at 6 P.M., the minimum 37*5 at 4 A.M. ; in a cow the 

 maximum was 39 0< 1 at 5 P.M., and the minimum 38 - 7 at midnight. 

 Corin and Van Beneden 8 have observed the daily variation in pigeons, 9 

 and find that the minimum is at 4 A.M. ; that from this time to 8 A.M. 

 there is a rise, then a fall to noon, followed by a rise to the maximum 

 at 4 P.M. ; the daily variation amounts to 2 0< 2. In the case of horses, 

 Hobday 10 finds that the rectal temperature at 10 A.M. is 37'6, and 37'9 

 at 5 P.M. ; in the case of the rabbit, cat, and dog, Carter n has shown that 

 there is a distinct rhythm of temperature, the maximum occurring in 

 the evening (7-11 P.M.) and the minimum in the morning (7-11 A.M). 



We may conclude that the daily variation in temperature is one of 

 the features of a corresponding variation in the activity of the tissues of 

 the body, as shown by the rate of the contraction of the heart, the 

 frequency of respiration, the intake of oxygen, the output of carbon 

 dioxide, the discharge of urea, and the capacity for muscular work. 



The influence of age. The temperature of newly-born infants and 

 animals is generally equal to, or even slightly higher than, that of their 

 parents, but it is much less stable, and is liable to much greater varia- 

 tions. 



Edwards 12 found that the temperature of newly-born pups, kittens, 

 and rabbits fell when they were removed from their warm surroundings, 

 and continued to fall until it reached a point a few degrees above the 



1 Patrizi, Arch. ital. de bioL, Turin, 1892, tome xvii. p. 134. 



2 Trout, Ann. Phil., London, 1813, vol. ii. p. 330 ; vol. iv. p. 331 ; Pettenkofer and 

 Voit, Ztschr. f. BioL, Miinchen, 1866, Bd. ii. S. 459 ; Fredericq, Arch, de biol., Gand, 

 1882, tome iii. p. 729. 



3 "Chemistry of Respiration," this Text-book, vol. i. p. 721. 



4 Ellen berger, " Vergleichende Physiologic derHaussaugethiere" 1892, Bd. ii.Th.2, S. 81. 



5 Veterinary Journ. , London, 1885, vol. xx. p. 311. 



6 "Die Verdaunngssafte und der Stoff'wechsel," Leipzig, 1852, S. 346. 



7 Deutsche Ztschr. f. Thiermed., Leipzig, 1875, Bd. i. S. 87. 



8 Arch, de bioL, Gand, 1887, tome vii. p. 265. 



9 See also Chossat, Mem. Acad. d. sc. de Vlnst. de France, Paris, 1843, tome viii. p. 540. 



10 Journ. Comp. Path, and Therap.. Edinburgh and London, 1896, vol. ix. p. 286. 



11 Journ. Nerv. and Ment. Dis., N.Y., 1890, vol. xvii. p. 782. 



12 "De I'influence des agens physiques sur la vie," Paris, 1824. 



