256 RAYMOND PEARL 



ences in mean dates of hatching as appear in table 4 as a pos- 

 sible factor in explaining differences in results obtained. 



In the case of the 1913 normal controls in the last column 

 of the table the hatching extended over a longer period of time. 

 But in using these birds as controls on hatching weight, growth, 

 etc., of the alcoholic chicks, only those hatched before May 1 

 have been used. The mean date of hatching of the April hatched 

 chicks of these 1913 controls is almost identical with the mean 

 dates for the chicks in the alcohol experiments. 



V. MORTALITY OF Fi CHICKS 



According to the results of earlier workers in this general 

 field it would be expected that there would be a decidedly 

 higher rate of mortality among the offspring of the alcoholized 

 parents than the normal. The data on this point are exhibited 

 in tables 5 and 6. In these tables the first column gives the 

 total number of chicks tagged with a numbered leg band and 

 put into a brooder. The circumstance that the numbers in 

 this column do not agree with the total numbers of chicks 

 hatched, as given in table 1, arises simply from the fact that 

 not every chicken which hatches is banded. Chicks which are 

 obviously malformed, or lacking in vitality to a degree which 

 makes their death within a few hours certain are not banded. 

 Also entirely normal chickens may not be banded because not 

 wanted for any further purpose. It very often happens that 

 after the available housing space is completely filled with 

 chickens one will carry through further hatches for the purpose 

 of adding more data on the fertility and hatching quality of 

 eggs and for no other purpose. When such chickens hatch 

 they are not banded, but immediately disposed of in another 

 way. Also some entirely normal chicks may fail to be banded 

 by oversight or accident, though this happens only very rarely. 

 The figures in the first column of tables 5 and 6 may be taken 

 as indicating chickens which started life as sound and healthy 

 individuals, so far as appearances indicated. ''Chicks missing" 

 recorded in the second column include in the first place those 

 that lost their leg bands through accident and thus could not 



