114 
Proceedings of the Royal Society of Edinburgh. [Sess. 
wall they had access to a large run outside. The pens were arranged in 
a row, and all were of similar construction. The floors were covered with 
a thick layer of straw, but no artificial heat was supplied in the winter 
months, so that the temperature of the air inside the pens was only a few 
degrees higher than that outside. 
From November till March, the ground being, as a rule, covered with 
snow for the greater part of that time, the hens were closed in the pens 
and prevented from getting out into the runs. During the night and in 
heavy rain and snow storms folding canvas screens were used to close up 
the pens in front. 
The food was the same all the year round, and consisted of cracked corn, 
wheat and oats (hard grains), and cornmeal, wheat middlings, wheat bran, 
oil meal, alfalfa meal, and green cut bone, all ground up together (soft food). 
They were also provided with mangles, oyster-shell and grit, and of course 
water. Each pen contained on an average about thirty hens and two 
roosters. Of the latter only one was free, the other being shut up in a 
small coop, and every two days they were interchanged. 
Six groups of hens were selected for these experiments, and each group 
located in a separate pen, viz. I. Barred Plymouth Rocks ; II. Buff 
Orpingtons ; III. White Wyandottes ; IV. Single Comb Brown Leghorns ; 
V. White Plymouth Rocks ; and VI. Rhode Island Reds. With the exception 
of the Leghorns, all were quiet birds, and when picked up and handled 
made little resistance. 
After some preliminary work in the spring, the regular observations 
were begun in October 1909, and were continued every month on the same 
individuals till September 1911. From April till October the hens were 
usually found in the runs, and were driven into the pens before the 
observations were made; but in the winter months, from November till 
March, they were nearly always found in the pens. 
Each hen was caught by an assistant, handed to the operator, and an 
accurate half -minute clinical thermometer was inserted into the cloaca and 
rectum to the depth of three inches, retained in position two minutes, and 
the rectal temperature then noted. The records were made, as a rule, 
on two successive afternoons, about the end of the third week of each 
month, and at the same hour for each pen throughout the series, with a 
few exceptions. Thus, Pen I. was examined between 1.30 and 2.30 p.m. ; 
Pen II. between 2.30 and 3.30 p.m. ; and Pen III. between 3.30 and 4.30 p.m. ; 
and on the following day, IV., V., and VI. were gone through in the same 
order. The temperature of the air in the pen was recorded in each case 
at the same time. 
