248 RAYMOND PEARL 



gave 1122 chickens from,2092 fertile eggs, or 53.6 per cent. The 

 figures for the treated matings, 63.0 per cent for treated cf d^ X 

 untreated 9 9 , and 72.3 per cent for treated cf d^ X treated 

 9 9 , are significantly higher than the normal hatching records 

 of the same year. These figures appear to demonstrate that 

 the alcohol (or ether) treatment had no deleterious effect upon 

 the hatching quality of the eggs of treated individuals. On the 

 contrary the fertile eggs of such individuals hatched distinctly 

 better than eggs of normal individuals. The correlation between 

 total germ dosage index and per cent of fertile eggs hatched gave 



r = +0.288 ± 0.138 



On account of the small series the probable error is large and 

 too much stress can not be laid upon the result. On the other 

 hand, small as the series is,^ the coefficient is more than twice 

 its probable error, and is to be regarded as probably significant. 

 So taken, it means that the larger the germ dosage the larger 

 the proportion of embryos which hatched, or, put the other 

 way about, the smaller the prenatal mortality. 



6. The last column of each table gives the percentage of 

 chicks hatched to all eggs set. For matings of treated cf cf' X 

 untreated 9 9 the final average percentage is 47.1. This is a 

 higher proportion of chicks hatched to eggs set than is given 

 either by the random sample of normal matings in table 2 

 (44.4 per cent), or by all cross-bred matings of 1915, in which 

 1122 chicks, or 42.7 per cent, were hatched from 2628 eggs set. 

 These figures show that in spite of the lower zygote forming 

 power in the treated matings, which has already been pointed 

 out, the hatching power of the eggs was enough higher than 

 the normal to bring the net hatching percentage above that for 

 normal, untreated birds. 



7. For matings of treated cf cf X treated 9 9 the case is 

 different. Here but 29.4 per cent of all eggs set produced 

 chickens. The excess hatching power in the eggs of this group 

 was not sufficient to offset the very poor fertility. 



8. The highest average percentage of chicks hatched to all 

 eggs set was from the matings of ether cf X untreated 9 9 the 

 lowest from the matings of methyl cf X methyl 9 9 . 



