LOCALIZED ANOMALIES IN HUMAN EMBRYOS 53 



of tliis sort ill an embryo I have designated in my paper on 

 monsters as a dissociation of the tissues. I picture to myself 

 something Hke the following sequence: when the ovum comes 

 into the uterus which is more or less diseased, it becomes some- 

 what poisoned and consequently does not implant itself well. 

 This naturally results in an irregular growth of the chorionic 

 villi; in turn the embryo is affected and it is only natural to 

 infer that the most direct influence would be through the vascu- 

 lar system, soon ending in poisoning of the heart and frequently 

 in the interruption of the circulation. In such specimens the 

 nutrition would reach the embryo through the exocoelom. In 

 fact one of the earliest indications of a pathological specimen is 

 an increased amount of magma in the exocoelom. Embryos, 

 which are thus cut off from the chorion, continue to grow in an 

 irregular manner; the tissues are more or less dissociated, and 

 the specimen as a w^hole is stunted. Hence the designation. 



In the fifth group (fig. 5), the process of stunting has pro- 

 gressed to such an extent that the extremities are almost 

 entirely lacking and only the head end can be recognized with cer- 

 tainty. On account of their shape, due to this extreme stunting, 

 we speak of these specimens as cylindrical embryos. Falling 

 frequently into this group are embryonic remnants which, 

 however, really do not belong there, since a primary examina- 

 tion with a binocular microscope does not permit of a sharp 

 differentiation between this and other cylindrical forms of 

 stunted embrj^os. Close examination wdth a microscope reveals 

 specimens of this sub-group to be, composed of a naked um- 

 bilical cord belonging to an older embryo which had disinte- 

 grated, or as seen in a few instances the embryo has been torn 

 off by mechanical means during abortion. As rapidly as the 

 sub-type is recognized, it is labeled in the card catalogue in 

 parenthesis (cord) so that in stud^dng these specimens we may 

 distinguish between the naked cords and the true cylindrical 

 forms of pathological embryos. 



\Mien the process of dissociation of the embryo begins in 

 still earlier stages than those belonging to the older groups (Xos. 

 0, 6, and 7), the result is a nodular body representing the embryo, 



