No. 563] EFFECT OF INTOXICATING MALE PARENT 643 



the Proceedings of the Prussian Academy of Sciences. 

 At that time he showed that when the unfertilized eggs 

 of a frog are treated for a certain time with radium rays, 

 these eggs, after being fertilized by normal spermatozoa, 

 develop abnormally. Hertwig also found that when the 

 milt or semen of the frog was exposed to the action of 

 radium for a certain time the spermatozoa swimming in 

 it were injured. When eggs were fertilized by these 

 sperm they always developed abnormally. The general 

 type of the abnormalities was the same whether the eggs 

 alone had been treated before fertilization or whether the 

 sperm was treated. When both eggs and sperm were 

 treated the developmental modifications were still more 

 pronounced, though Hertwig claims that the deformities 

 were of a similar type to those which occurred after 

 treating only one of the cells. 



Since that time Oscar Hertwig with his son and daugh- 

 ter have extended and analyzed these experiments in a 

 comprehensive fashion. When the sperm of a number of 

 amphibians, frog, toad and salamander, are exposed for 

 five minutes to 5.3 mg. of radium bromide, normal eggs 

 fertilized by such sperm give defective embryos, the 

 defects being generally shown by the central nervous 

 system. They are really of the nature of developmental 

 arrests or degeneration. 



If the spermatozoa are exposed for fifteen minutes the 

 effects on development are still more marked. When, 

 however, the sperm in salt solutions are treated inten- 

 sively for 2 and 3 hours between two mesothorium cap- 

 sules, the results are most surprising. In one experiment 

 almost all the eggs fertilized by such sperm went nor- 

 mally, and in other experiments they went almost normal 

 but slow, yet they were extraordinarily better than eggs 

 that were fertilized by sperm that had been treated for 

 only five minutes. After three weeks the radium larva 

 were still behind the control. Hertwig concluded that the 

 spermatozoon had been so injured by the intensive treat- 

 ment that it could no longer take part in development. 



