GENETICS: R. PEARL 
681 
inactivating, the weak germ cells and pemitting only the strong, vigor- 
ous, and resistant germ ceJls to form zygotes. This results, in forms 
like the fowl having germ cells rather highly resistant to alcohol, in a 
small but superior progeny from alcoholists. On the other hand, in 
forms like the guinea-pig, whose germ cells are known to have a relatively 
low resistance to alcohoP it results in the formation not only of a 
relatively small progeny, but also a weak and abnormal one, since the 
germ cells which are not entirely inactivated by the agent are still 
not sufficiently resistant to be uninjured by it. 
A rather striking confirmation of this interpretation was obtained 
in an experiment carried out this past summer. I reasoned that if 
the above interpretation is correct, alcohol ought to act as a selective 
agent in the same sense on the very young zygotes, killing the weak 
and permitting the survival only of the strong provided the appropriate 
dosage could be found. To test this idea the following experiment was 
performed. Two incubators were used, each containing at the out- 
start 390 eggs. These eggs were selected with the utmost care to en- 
sure likeness of age, of strain, and of other characteristics in the two 
lots. In one incubator 40 cc. of 95% ethyl alcohol were evaporated 
beneath the eggs daily. In the other incubator no alcohol was used. 
At the end of 7 days 130 eggs, designated as Lot 1, were removed from 
the alcohol incubator and allowed to complete their development in 
a normal non-alcoholic incubator. At the end of fourteen days the 
remaining eggs (after testing out infertiles) of Lot 2, which originally 
contained 130 eggs, were removed from the alcohol incubator and fin- 
ished their development without further dosage of alcohol in a nor- 
mal incubator. Finally Lot 3, originally containing 130 eggs, was sub- 
jected throughout the 21 days of incubation to the daily dosage of al- 
cohol fumes. At hatching all the normal chicks from both incubators 
were put together in the same house and brooder and given throughout 
life the same treatment as to feed, etc. Careful account was kept of 
mortality, each chick, being marked so that it could be told from which 
lot it came. The conditions of brooding were purposely made bad so 
to obtain a maximum severity of post-embryonic environmental con- 
ditions with a consequent high absolute mortality rate. The results 
are set forth in Table 4. 
