I5« 



Scientific Proceedings (67). 



mouth. These guinea-pigs were mated, lead females with normal 

 males and lead males with normal females. In order to check the 

 results as efficiently as possible control matings were made of 

 normal males with normal females under the same feeding and 

 housing conditions as the lead poisoned pigs, and for the same 

 reason the normal females were bred alternately to lead males and 

 to normal males. The dosage of lead was controlled by frequent 

 weighings in order that the general nutrition should not be 

 seriously impaired. 



A total of 93 matings yielded 170 offspring. Of these, 32 

 matings of normal male with normal female produced 58 offspring 

 with an average birthweight of 81.5 gms. From 34 matings of 

 lead male with normal female 65 young were produced with an 

 average birthweight of but 66.3 gm. From 27 matings of normal 

 male and lead female, 47 young were produced with an average 

 birthweight of 69.3 gm. Nine offspring of lead males died in the 

 first week against two offspring of normal males dying in that 

 time. Eight young of lead females were stillborn against three 

 stillborn from normal females bred to normal males. 



From the entire series of matings the following conclusions 

 seem to be justified: 



1. In chronic lead poisoning in guinea pigs there is a definite 

 blastophthoric effect which can best be demonstrated upon the 

 male germ plasm. This effect manifests itself in some instances 

 by sterility without loss of sexual activity, by a reduction of 20 

 per cent, in the average birthweight, by an increased number of 

 deaths in the first week of life and by a retardation in development 

 such that these pigs remain permanently underweight. 



2. From the apparent recovery of the germ plasm some time 

 after stopping the administration of lead it seems that the dele- 

 terious effect must be suffered especially by that portion of the 

 germ plasm which is undergoing maturation and not by that which 

 is stored in the primary germinal epithelium. However, final 

 judgment upon this point must be withheld. 



