6G0 GEOFFREY SMITH. 



was observed in tlie serum drawn from the injected bird, nor 

 did this serum stop the motion of spermatozoa any quicker 

 than in tlie case of normal birds. The various dilutions of 

 the serums obtained from iujected and non-injected birds 

 also gave similar results. 



It was therefore found in the limited experituents per- 

 formed that 110 immunising process could be detected as 

 the result of the injections, and this negative effect is in 

 accordance with the observations on health, comb growth, 

 and fertility, as affected by the injections. 



Summary or Results. 



(1) The injection of testis extract into hens was found to 

 have an entirely negative effect on the increase of the comb 

 in eight out of nine adult and young hens when compared 

 with the fluctuations in growth observed in control birds. 

 In one case the injected hen showed an increase of comb 

 slightly greater than any observed in the control birds,^ but 

 the comb in this bird did not show the constant shrinkage, 

 after cessation of injections, observed in the cases cited by 

 Dr. C. E. Walker, and regarded by him as an essential 

 feature of the experiment. 



(2) The injections had no observable effect on the health, 

 body-weight, fertility, blood properties, or any other features, 

 although very large quantities were administered over periods 

 varying from fifteen to seventy-five days. 



(3) The result of the experiments is to show that, although 

 Dr. Walker^s observations were doubtless correct, his con- 

 clusion that the increase of the comb was due to the testis 

 extract injected was erroneous. There is, therefore, no 

 evidence that the testis contains an internal secretion wliich, 

 when injected into the female, can call forth the production 

 of any of the male secondary sexual characters. 



' Since the MS. was in proof, a control bird of two and half years age 

 lias given a percentage increase in comb of 130 in a period o£ twenty 

 days, tluis exceeding that of any of the injected birds (see note on p. 7). 



