1911-12.] Body Temperature of Diving and Swimming Birds. 21 
his readings. He had a special thermometer constructed for the expedition 
giving direct readings to the hundredth of a degree centigrade, and made 
very strong, presumably to withstand the strain put upon it while in the 
rectum, due to the struggles of the bird. It was not a maximal or clinical 
thermometer, and required to be read in situ. 
He does not give much detail as to how the birds were secured, but they 
were all examined alive and uninjured with a few exceptions. Those that 
were wounded, unless only very slightly, were discarded. Some were 
caught on a baited hook and line and the rectal temperature taken im- 
mediately after they were hauled on board. All these wild birds must 
have been greatly agitated, and must have struggled violently when 
forcibly held while the thermometer was being introduced into the cloaca 
and rectum (where it was retained not less than three minutes) and the 
temperature recorded, although Martins makes no mention of this circum- 
stance and makes no allowance for any possible error that might arise 
from it. Notwithstanding this, he found that the rectal temperature of 
these wild birds was distinctly lower than that of the domestic cluck. 
He also made a large number of observations on the domestic duck and 
goose in different parts of the country (France), and on many species of the 
Palmipedes confined in the Zoological Gardens in Paris, and from these he 
drew important deductions regarding the influence of sex, age, external 
temperature, and alimentation on the body temperature. 
With regard to sex, he found that the mean rectal temperature of fifty 
drakes was 41° - 915 C. and that of sixty ducks (female) 42 c, 264 C., showing 
a difference in favour of the female of 0 o, 349 C. While the mean figure 
was higher, however, the temperature of the female showed greater varia- 
tion, the range (difference between the highest and the lowest readings of 
the whole flock) being almost double that found in the males — 2° '55 C. and 
l o, 80 C. respectively. 
The influence of age is not appreciable. Ducklings hatched in the spring 
are considered to have reached the age of puberty in the autumn, that is, 
when about six months old. In two flocks of ducks, males and females 
mixed, the one including thirty-one birds from four to six months old, the 
other thirty-seven birds from seven months to two years old, he found 
the mean temperature to be almost identical — 42 o, 012 C. and 42°011 C. re- 
spectively. Throughout the first two years of life, therefore, the tempera- 
ture does not appear to be affected by the age of the individual. In the 
first group, even before the females had begun to lay eggs, there was a very 
slight sex difference in favour of the female, but not nearly so great as in 
the second group of older birds, as the subjoined table shows 
