292 THE TREND OF THE RACE 
offspring. Rennert has attempted to express in statistical terms 
the varying degrees of gravity of the prognosis of cases in which 
at the moment of conception both parents are the subjects of lead 
poisoning, also where one alone is affected. The malign influence 
of lead is reflected upon the foetus and on the continuation of the 
pregnancy 94 times up to 100 when both parents have been work- 
ing in lead, 92 times when the mother alone is affected, and 63 
times when it is the father alone who is working inlead.... In 
his studies upon hereditary degeneration and idiocy, Bourneville 
places house-painters in the unenviable first rank of the occupa- 
tions followed by parents of mentally weak children.” (Diseases 
of Occupation, 202-203.) 
These results, while not very conclusive as to permanent 
injury to the germ plasm, are naturally suggestive of such action. 
The possibility of true heritable modification being produced 
by lead has been tested by Cole and Bachhuber ! on fowls and 
rabbits and by Weller on guinea pigs. Cole and Bachhuber 
administered lead only to the males. The offspring of the poi- 
soned male rabbits showed less weight and a higher mortality 
than the offspring of normal individuals. In the fowl it was found 
that eggs fertilized by poisoned cocks failed to develop much more 
frequently than those fertilized by normal males, and the chicks 
from poisoned male parentage had a higher mortality both before 
and after hatching. 
Weller found that the offspring resulting from mating poisoned 
male guinea pigs with normal females were about 20 per cent less 
in weight than the controls, that more of them died during the 
first week and that the survivors showed a general retardation. 
Thus far we are not in possession of facts indicating that injury 
due to lead is carried beyond the first generation. If the results 
of male plumbism are due to injuries to the chromatin material of 
the sperm cells it seems probable that they would be transmitted 
to subsequent generations. Analogy with the effects of male 
alcoholism in guinea pigs would also support this conclusion. 
Further work on this important problem is much to be desired. 
1 Proc. Soc. Exp. Biol. Med. 12, 24-29, 1914. 
