22 
Proceedings of the Royal Society of Edinburgh. [Sess. 
31 ducks , 6 months old and under. 
Mean temperature of 16 males . 41° ’998 C. 
,, „ 15 females . 42°*025 C. 
Difference . 0°'027 Difference . 0 o, 533 
From a comparison of these two sets of figures it may be concluded that 
the temperature of the female rises after puberty, while that of the male falls. 
The temperature of the surrounding medium was not found to have 
much effect on the body temperature of the birds. From a series of 
observations made on nine individuals — five ducks and four drakes, — first 
in winter, when the temperature of the air was below zero, and second in 
summer, when the outside temperature was 20° C. and over, he concluded 
that there was a difference of 0°T67 C. in the mean rectal temperature in 
favour of the winter, the figures being 42°T95 C. (winter) and 42 o, 028 C. 
(summer). He is inclined to believe, however, that this apparent rise of 
the body temperature in winter is not so much influenced by the tempera- 
ture of the surroundings as by the increased activity of the bodily functions, 
since l’epoque des amours coincide avec celle des plus grands froids de 
l’hiver, et l’excitation qui en resulte entretient la chaleur en activant la 
circulation. Je ne serais done pas etonne qu’on ne trouvat pas de difference 
entre la temperature des Palmipedes, en hiver et en ete.” This, he believes, 
more than counteracts the fall in body temperature which might be 
expected to arise from the excessive cold, were that influence operating 
alone. It seems, however, that the number of individuals and of observa- 
tions on them are much too few to form the basis of any such far-reaching 
conclusion. 
Regarding the influence of diet, he agrees with Chossat’s * findings in 
pigeons, viz. — that in birds deprived of solid food for five days there was a 
decided fall at the end of twenty-four hours ; this was followed by a very 
slight rise during the three successive days, and at the end of the fifth day, 
when the experiment was stopped, there was again a slight fall. 
Of the possible influence of muscular exercise on the body temperature 
he makes no mention, and does not take this factor into consideration at all 
as affecting his results in any way. This omission detracts a good deal 
from the value of his work, more particularly in the case of the wild birds 
which he examined. 
In 1854 Brown-Sequard f had the opportunity of examining the body 
temperature of some Palmipedes in the South Atlantic off the Cape of Good 
* Chossat, Annales des sciences naturelles , 2nd series, t. xx., 1843, pp. 181 and 294. 
t Brown-Sequard, Journ. de Physiol ., t. i., 1858, p. 42. 
37 ducks , from 7 months to 
2 years old. 
12 males . 41°‘745 C. 
25 females . 42° - 278C. 
