2 9 2 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 fcetus 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 in lead. ... 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 1 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. 



x Proc. Sex;. Exp. Biol. Med. 12, 24-29, 1914. 



