1911-12.] Effects of Seasonal Changes on Body Temperature. Ill 
readily influenced by external conditions, particularly the temperature of 
the air, and give no reliable information regarding slight changes in the 
temperature of the deeper parts of the body. 
In the cool season of the year, J ousset * found that the average tempera- 
ture of the natives was from two- to three-tenths of a degree higher than in 
the warm season. 
Bosanquetf made observations on his own rectal temperature, four 
times a day, at the same hours (9 a.m., 2, 7, and 10 p.m.)for a period of three 
years, with only a few interruptions. Dividing the year into thirteen lunar 
months, beginning in the middle of June,*and taking the average temperature 
for each month, he obtained the following figures: — 98*75° F., 98 75°, 98*80°, 
98*72°, 98-80°, 98*89°, 98*92° (December), 98*90°, 98*97°, 98*90°, 98*95°, 98*82°, 
and 98 85°. Thus, in his case, the highest maintained average temperature 
occurred in the winter and early spring months, but the curve plotted out 
from these figures would show only a slight degree of variation throughout 
the year, the range being 0*25° F. 
In the case of homoiothermal animals other than man, few observations 
have been made. W. F. Edwards f made experiments upon a great number 
of sparrows “ taken at different seasons of the year, which is preferable to 
keeping these creatures in captivity for any length of time. The mean 
temperature of these birds rose progressively from the depth of winter to 
the height of summer, within the limits of from two to three degrees centi- 
grade. ... In the month of February the mean temperature of these birds 
was found to be 40*8° C., in April 42°, and in July 43*77°. The temperature 
from this time began to decline, and followed in the same ratio in which it 
had increased, the sinking temperature of the year.” No further statement 
than that just quoted is given with regard to the conditions under which the 
observations were made, e.g., as to how the birds were caught, the hours of 
the day when the temperatures were taken, etc. These small birds have a 
marked diurnal variation,! and it is important in comparative work of this 
kind that the readings be taken as nearly as possible at the same hours on 
successive days. 
In 1838 John Davy|| investigated the influence of the seasons on the 
rectal temperature of the sheep. On January 26, at noon, the mean 
temperature of three ewes was 104° F. The air temperature had been 
* Jousset, Arch, de me'd. nav., Paris, 1883, t. 40, p. 124. 
t Bosanquet, Lancet , London, 1895, vol. i. p. 672. 
+ Edwards, art. “ Animal Heat,” in Todd’s Cyclopaedia of Anatomy and Physiology , vol. ii. 
p. 659. 
§ Simpson and Galbraith, Journ. Physiol., xxxiii., 1905, p. 225. 
|| Davy, Researches, London, 1839, vol. i. p. 208. 
