Scientific Proceedings (108). 



ultimate destruction of these tissues. In our work an attempt 

 was made to study this destructive influence on mammalian 

 embryos in utero, in the hope that a partial or complete destruc- 

 tion of one or more tissues might lead to definite abnormalities 

 or malformations in these fetuses. 



Bagg had lately used a method of applying radium, which 

 was described in the Journal of Cancer Research, Vol. V, 1920. 

 Radium emanation, carried in a very small amount of saline solu- 

 tion, was injected in measured quantities into adult rats, either 

 subcutaneously or intravenously. This solution contained all 

 the properties of the radium metal itself, and, no doubt, the re- 

 sulting physiological changes were due mainly to the activity of 

 a-rays. Such an injection produced peculiar destructive changes 

 in the inner organs of the animals. 



The same method was used in our experiments. After long 

 experimentation we found that a dose of 5 mc. (= milli-curies, a 

 standard unit in radium experimentation) was about the optimal 

 dose. Such an amount was injected into female rats, pregnant 

 and non-pregnant, with the purpose of either injuring the ovarian 

 or uterine tissues, or, in case of pregnancy, the embryonic tissues. 

 While the results were not those which we expected, viz., the 

 production of various types of monstrosities, yet a definite in- 

 fluence of radium on the fetal and placental tissues was noticeable. 

 Radium-treated rats were killed at different periods of pregnancy, 

 so as to procure a series of fetuses of various ages. 



The most destructive results of radium emanation, injected 

 subcutaneously, were seen in a number of pregnant females, in 

 which the embryos were killed in the uterus and, instead of being 

 aborted, remained attached to the uterine wall and were gradually 

 absorbed (group I). Whether the embryos were killed primarily, 

 or their death was due to the destructive influence of the radium 

 on the maternal, placental tissues, cannot, of course, be deter- 

 mined. Probably the first assumption is correct, since other 

 findings (group II) showed, that the toxic agent does pass the pla- 

 centa and affects the embryos directly. 



A number of such partially absorbed embryos were found, the 

 age of which, naturally, could not be determined. Judging from 

 the sizes of their respective placenta?, however, development must 



