596 GEOFFREY SMITH. 



bird during injection than iu the control birds. The comb of 

 the injected bird No. 5, which showed a large increase during 

 injection, not only did not constantly shrink after the injec- 

 tions ceased, but actually, five months subsequently, attained 

 its maximum size. Again, in these birds there was no 

 correlation between growth of comb and general body- 

 weight. 



In Experiment No. o nine young birds, three months 

 old, of the same parentage and brought up together, were 

 used. They belonged to the Indian Jungle fowl breed, and 

 all had similar combs. Three birds, Nos. 11, 12, and 13, 

 were injected each with 39 c.c. extract in a period of twenty- 

 one days, during which period their combs showed a per- 

 centage increase of 45, 02, and 30 respectively. The six 

 control birds showed the following percentage increases 

 during the same period : 53, 00, 02, 38, 14, and 30. 



In case it might be ai'gued that the effects of the injection 

 might show themselves some time after the cessation of 

 injection, measurements of the comb were continued for a 

 month after the last injection. In that month the injected 

 birds gave percentage increases of 20, 20, and 28, while the 

 control birds in the same period gave 97, 9*8, 13, 35, 36, 

 and 30. 



The result of this experiment, therefore, conclusively showed 

 that in young birds of three months old the injection of 

 39 c.c. of testis extract in a period of twenty-one days had 

 absolutely no effect on the growth of the comb. 



Summarising the results of the three experiments it will 

 be seen that out of nine injected birds, eight gave 

 absolutely negative results when compared with 

 the controls. It cannot be objected to these negative 

 results that the hens were not injected with enough extractor 

 for a sufficiently long period, since all of them received as 

 much, or in most cases more, and for an equal or longer 

 period than the bird No. 1, which might be claimed as 

 showing positive results. This bird showed an increase 

 greater tliau iu any of the controls (113 per cent.), but con- 



