226 CHARLES R. STOCKARD 



In his last study on the frequency of locaUzed anomalies in 

 human embryos and stillborn infants, the data from a thousand 

 specimens are recorded. 



Mall's method of arranging this material may be considered 

 in brief in order to attempt fitting it into our above conclusions. 

 The material was primarily divided into normal and pathological 

 specimens. Some of the 'normal' may possess localized anomal- 

 ies, such as cyclopia, etc., and a study of the pathological group 

 Mall believes justifies this inclusion of localized anomalies among 

 the normal embryos. 



The pathological group was then subdivided into seven classes 

 of specimens: first, those consisting of only degenerate choi ionic 

 villi ; second, of only the chorion with the extra embryonic coelom ; 

 third, of the chorion and amnion; fourth, of the embryonic mem- 

 branes containing a nodular embryo; fifth, of cylindrical embry- 

 os; sixth, stunted embryos, and, seventh, dried and deformed or 

 soft and macerated specimens. The series thus begins with the 

 most degenerate conditions and passes on to those specimens 

 which maintained their integrity fairly well, though evidently 

 malformed and dead for some time before being aborted. Un- 

 questionably, all members of such a series have suffered develop- 

 mental arrests of the severest types. In some cases the arrest 

 has come at an early stage and been followed by a disorganiza- 

 tion or cytolysis and subsequent absorption of the embryonic 

 material. In guinea-pigs one frequently finds similar stages of 

 embryonic degeneration in utero, and here also the placenta and 

 membranes are the last parts to disappear. In almost all of these 

 cases portions of the pregnancy must have remained in the uterus 

 for some time after the embiyo died before being discharged. 



If these pathological specimens are primarily due to develop- 

 mental arrests, what, if any, evidence is there that conditions 

 may have existed which could probably have induced such 

 arrests? Or, is there evidence that human embryos are affected 

 very readily by strange conditions? Very valuable data bearing 

 on both of these questions are supplied. In the one thousand 

 specimens considered, about 33 per cent of the ova and embryos 

 from the uterine lot w^ere pathological, while as many as 66 per 



