122 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Table XXXI. 
A. Cock. 
A. Capon. 
Percentage 
Increase. 
B. Cock. 
B. Capon. 
Percentage 
Increase. 
Femur 
9 
9-8 
9% 
7-4 
8-3 
12% 
Tibia . 
13*4 
15T 
12-6% 
12-2 
13-2 
8-2% 
In all these birds the epiphysis and diaphysis had joined, but Sellheim 
(20) has shown that in the capon there is delay in the completion of the 
process of endochondral ossification. 
Observation B2(l). 
The Effect of Castration upon Guinea-pigs. 
Three guinea-pigs of the same litter, age 45 days, were taken. One 
was left entire, two were castrated. 
The weight of the animals was — 
No. 1, castrated 
. 325 grammes. 
No. 2, castrated 
. 400 
No. 3, entire 
. 355 
After the operation the three animals were placed in one cage, and were 
treated absolutely alike. They were weighed regularly, and an interesting 
series of observations was recorded. At first the castrated animals got 
rapidly heavier. No. 1, castrated, which to start with weighed 30 grammes 
less than No. 3 entire, surpassed him in weight, and at the end of four 
months was the heavier by 150 grammes. 
No. 1, castrated . . .770 grammes. 
No. 3, entire .... 625 „ 
For the next four months the weight of these animals remained 
stationary, at the end of which time they were killed. 
No. 2, castrated, which to start with weighed 45 grammes more than 
No. 3 entire, gained weight up to three months, at which time he weighed 
655 grammes. No. 3, entire, at the same time weighed 595 grammes. 
From the third month on, the weight of No. 2, castrated, did not materially 
alter until the end of the eighth month, when he was killed. As stated 
above, No. 3, entire, increased in weight to a total of 625 grammes. 
No. 2, castrated . . .655 grammes. 
No. 3, entire . . . 625 „ 
