112 Proceedings of the Royal Society of Edinburgh. [Sess. 
below freezing-point continuously for four days previously, and when the 
observations were made it was 29° F. in the outhouse where the sheep were 
confined, and into which they had been driven from the marsh the evening 
before. On January 29, between 1 and 2 p.m., outside temperature 46° F., 
the mean temperature of two sheep, also ewes, was 105° F. In relation to 
one of these he says that : “ the second sheep was in an irritable state ; the 
lungs abounded in granular tubercles, yet the animal was in excellent 
condition.” The next observations were made on March 16, when the 
temperature of the air was 51° F. and the mean rectal temperature of four 
individuals (females) was 105‘5°. On May 23, air 63°, the mean tempera- 
ture for three individuals was 105° ; on August 21, air 70°-72°, for eight 
individuals (two of which were lambs about fourteen weeks old), it was 
105’44°, and on August 28, when the thermometer stood at 79° F. in the 
shade, the mean for four individuals was 105’5°. These results are not 
very consistent, but they appear to show that body temperature of the 
sheep is a little higher in the warm weather of summer than in the 
moderately cold weather of the English winter. It must be remembered, 
however, that each set of observations was made on a different group of 
individuals, just before they were slaughtered, and that in many respects 
the conditions were not similar for each group. 
Present Investigation. 
The causes underlying the diurnal temperature changes that are present 
in a greater or less degree in all liomoiothermal animals have not yet been 
clearly established. By many it is believed that these diurnal variations 
are due almost entirely to influences acting on the body from without ; by 
some it is held that they are mainly dependent on periodic or cyclical 
changes within the body. The question must still be regarded as an open 
one, although the bulk of the evidence brought forward in recent years 
appears to give strong support to the first view. In an important contribu- 
tion to this subject, Lindhard * comes to the conclusion that the “ curve of 
temperature variations is determined by work and mode of living, that the 
astronomical division of day and night is without importance in this regard, 
and that an inherited form is consequently out of the question, a mysterious 
periodicity even more so.” 
In the light of the “ doctrine of phases ” f it is not unreasonable to 
* Lindhard, loc. cit. 
t For information regarding the application of this doctrine to physiology, consult a 
paper by Zwaardemaker and Dakhuysen, read before the International Medical Congress at 
Budapest, August-September 1909, and an article in the British Medical Journal , February 
19, 1910, p. 461. 
