284 RAYMOND PEARL 



to be highly improbable. In the first place my results agree 

 fully with Stockard's so far as concerns the effects produced 

 upon the treated animals themselves. This would imply that 

 the physiology of reproduction is alone so different in kind in 

 birds and mammals that it is differentially affected. But it 

 seems to me that all we know about the matter agrees in indi- 

 cating that the fundamentals of ovarian and testicular physi- 

 ology are essentially the same in birds and mammals. 



A second possibility is that while the effect of alcohol upon 

 the germ cells is the same in kind in birds and mammals, it 

 differs markedly in degree in the two cases, the germ cells of 

 birds being much more resistant to injury by alcohol than those 

 of mammals. This seems to offer a valid explanation of the 

 apparent discrepancy in results, and I shall return later to a 

 more detailed discussion of it. 



A third possibility is that what has here been called the 

 total germinal dosage (cf. I), is too low to produce any effect, 

 and that with higher dosage harmful results would have mani- 

 fested themselves. There are three things here to consider. 

 One is that the average duration of treatment prior to the birth 

 of offspring (i.e., germinal dosage) is certainly as long, and per- 

 haps even longer than that which has been definitely shown by 

 Stockard to be necessary to produce deleterious results in guinea 

 pigs. While Stockard has not, so far as I am able to find, any- 

 where given definite figures for total germinal dosage in con- 

 nection with particular individual matings, it is clear from the 

 general context of all his papers that a few months continuous 

 treatment of the parents with alcohol prior to conception is 

 amply sufficient to injure the germ cells to the point where 

 defective offspring are produced. In some cases he apparently 

 has got results with very short duration of treatment. Thus 

 he says (35, p. 656): ''A number of experiments in which the 

 treatment of a female was commenced at the beginning of 

 pregnancy have so far given rather indefinite results, although 

 a slight effect may be indicated." This of course is a great 

 reduction of germinal dosage and no one could expect marked 

 or definite results. Stockard points out in many places in his 



