THE VILLI IN ABORTUSES. 319 



Eternod (1909) divided the development of the villi into five phases: (1) a 

 primordial, avillous syncytial phase; (2) an avillous trophodermic phase; (3) a 

 trophodermic, transitory, zonal villous phase; (4) a diffuse, placental villous phase; 

 and (5) a diffuse, chorionic, and chorion-frondosum phase. Eternod placed the 

 conceptuses of Peters and Leopold in the second or avillous phase, in spite of 

 the fact that both these vesicles had short villi containing mesenchyme. His 

 third phase was illustrated by the specimens of Reichert and Ahlfeld and one of 

 his own in which the villi had an annular or equatorial distribution. According 

 to Eternod, the portions of the chorionic vesicle which later are in contact with 

 the basalis and capsularis are devoid of villi during this phase, which he regarded 

 as a transitory, but nevertheless necessary, phase. He believed that the bare 

 areas upon the chorionic vesicles resulted from inequalities in the expansion of 

 the chorion, and stated that in the specimen of Reichert and in one of his own, the 

 ventral or capsular bare area is less evident than the basal or dorsal, as he called it. 

 He believed that the ventral bare area disappeared earlier than the dorsal, only 

 to reappear again, however, when the chorion laeve developed. Although he was 

 not absolutely decided in this matter, Eternod believed it improbable that young 

 villi are interpolated between the older, concluding that the chorion frondosum is 

 enlarged through the addition of villi at its periphery with far greater regularity 

 than heretofore suspected. 



The fourth phase in the development of the villi, according to Eternod, occurs 

 in vesicles with a length of approximately 9 to 16 mm. In such the villi are 

 branched and their terminations fused by trophoderm. The fifth phase follows 

 the fourth very quickly, for it is said to be present in chorionic vesicles 17 mm. in 

 size, and to be characterized by great inequalities of growth- and by far greater 

 complexity in the basal area than in that of the capsularis. 



Dandy (1910), in describing a chorionic vesicle 16 by 14 by 12 mm., found the 

 villi branched and about 0.1 mm. thick and 1.25 mm. long. He stated that they 

 "are more numerous at the point of attachment of the Bauchstiel and gradually 

 fade away on all sides until, finally, a clear zone results from their absence on 

 the opposite pole. . . . From the epithelial layer of the chorionic membrane 

 and villi numerous buds develop, some from the syncytial layer alone, others from 

 both layers of the epithelium. These represent proliferating and new forms of 

 villi." 



Miller (1913), in describing a conceptus 0.83 mm. in greatest diameter, stated 

 that the mesodermic villi were as yet absent, and that the Langhans and syncytial 

 layers were structurally identical, although already distinct. Lazitch (1913) 

 called attention to the fact that the conceptuses described by Peters, Leopold, 

 Strahl and Beneke, and Fetzer showed the earliest villi to be mesodermal buds, and 

 that the specimen reported by Jung already showed the presence of dichotomy. 

 Lazitch stated that the villi are less irregular and more cylindrical in form in the 

 fifth month, and that curious forms, such as "little-horns," are rare. She stated 

 further that the villi became long at term and possessed fewer buds, some of which 

 looked as though they were branches arrested in development. Lazitch also found 



