COMPENSATORY HYPERTROPHY OF THE TESTES. 459 



The two papers cited above report a certain difference in the 

 results obtained. The discrepancy may be due to the time the 

 surviving gonad was retained and also to the age of the animal 

 at the time of operation. 



We became interested in the problem of compensatory hyper- 

 trophy of the testis as applied to the material used in the labora- 

 tory for a variety of experiments, pure bred Brown Leghorn 

 cocks. The experiments were begun early in July 1924 and 

 terminated at the end of April 1925. 



We were guided in outlining the course of the experiments by 

 the following points of view : (a) the appearance of compensatory 

 hypertrophy as such after the removal of one of the pair of 

 gonads; (&) the influence of the age of the birds at the time of the 

 operation on the possible increase in size of the surviving gonad ; 



(c) whether the time that the surviving gonad is retained is of 

 effect on the degree of possible hypertrophy taking place. 



(d) Finally we wished to determine if there was a significant 

 difference in the amount of the hypertrophy taking place in the 

 right or the left gonad after unilateral castration. 



After the experiments were terminated and the data completed 

 we became acquainted with a paper by Benoit '25 (3). This 

 author carried out a series of unilateral castrations on \Vhite 

 Leghorns; the operations were performed on three young birds 

 of 18-20 days of age, on one young bird aged two months and 

 on two birds aged seven months each. Control gonad weights 

 were stated for the groups of different ages. According to the 

 results obtained by Benoit, there is a very real increase in the 

 weight of the surviving gonad when castration is carried out at 

 an early date. In the three cases where unilateral castration 

 was performed in baby chicks the surviving testes were retained 

 for about twelve months. At this date each one of the hyper- 

 trophied testes weighed approximately as much as, or slightly 

 more than, both testes of the control. The surviving gonad of 

 the cockerel which was operated upon at two months was 

 retained for seven months, at the end of this time it weighed 

 almost 50 per cent, more than the control pair of testes, but it 

 is important to observe that "controls" of this age vary greatly 

 among themselves. Benoit observed no significant hypertrophy 



