464 L. V. DOMM AND MARY JUHN. 



The three surviving right testes on the other hand showed no 

 such increase in size, and in fact did not differ significantly from 

 a single control testis. 



The second group of young cockerels was castrated at sixteen 

 weeks and the results are tabulated in Table II. The surviving 

 testes were retained eight, sixteen and twenty-four weeks re- 

 spectively. It was originally planned to observe the degree of 

 compensatory hypertrophy to forty-eight weeks at which time 

 the birds have been fully mature for about sixteen weeks. How- 

 ever a number of birds died owing to one cause and another so 

 that the last data were obtained on cocks aged forty weeks and 

 only on two right testes. 



There is no observable compensatory hypertrophy either of the 

 right or the left testis when the glands were retained only for 

 eight weeks after the operation. There was an increase in size 

 during this period but this was identical with the control glands. 

 After a period of sixteen weeks, however, both the left and the 

 right surviving testes show a considerable degree of compensatory 

 hypertrophy, the left testis being heavier than both testes 

 together of each of the two control pairs; the right testis on the 

 other hand, while it exhibited a high percentage weight, was only 

 slightly heavier absolutely than a single control testis. Three 

 birds were available for observation after twenty-four weeks, 

 two of them having a right testis each while the third served as 

 control. Each of the two right testes weighed about 75 per cent, 

 as much as the control pair, the degree of compensatory hyper- 

 trophy on a percentage basis being similar to the amount observed 

 after sixteen weeks. 



Table III. gives the data for the next group. The cockerels 

 in this group were unilaterally castrated at twenty-four weeks 

 and then observed to forty-eight weeks at intervals of eight, 

 sixteen and twenty-four weeks, respectively. After eight weeks 

 the surviving left testis showed a certain degree of hypertrophy, 

 weighing much more than one of the control pair of gonads and 

 only slightly less than the other. The right testis had not 

 increased at all as compared with the normal. The same is true 

 after sixteen weeks; the left surviving gland is larger than any 

 one testis of the control pairs but not as heavy as one of the 



