282 STUDIES ON PATHOLOGIC OVA. 



von Winckel also spoke of a slowing in development before the death of the embryo 

 occurred. Taussig (1903) stated that both Breus and Gottschalk concluded that 

 retained "ova" grow, and Graefe (1896) called attention to the opinion of Veit that 

 "ova" may continue to grow after the death of the embryo, but added that the 

 existence of bare areas and the bunching of villi in some of the retained specimens 

 argue against the conception of His that "ova" with these characteristics have 

 continued to grow for some time. 



No one seems to have suggested that the entire embryo may continue to grow 

 after cessation of the fetal circulation, but Wallenstein (1897), who made a careful 

 microscopic examination of some early abortuses, not only believed that cellular 

 proliferation can occur in the embryo after its death, but that either the lateral 

 or the dorsal or ventral halves may continue to grow independently of each other 

 after the death of the cyema. Wallenstein believed, even, that the cyema can 

 become diseased after its death, and concluded that intravascular cells not only 

 outlive the rest of the cyema, but that they proliferate and invade the dead or 

 dying tissues of the latter. 



Schaeffer (1898) also stated that the chorionic and amniotic vesicles continue 

 to grow, provided death of the embryo occurs before the fourth month, and Mall 

 (1900, 1903) also spoke in favor of growth in them after death of the embryo. 

 Engel (1900) believed that the caudal half of the body of an embryo may continue 

 to grow after the cephalic half has died. However, Engel's conclusion regarding 

 the proliferation of cells was based largely upon the observation that the volume 

 of the disintegrating central nervous system was too great to be accounted for 

 merely by the cells which normally compose it. 



Giacomini (1894) believed that even the isolated amnion may continue to 

 grow and that the chorion may continue to live after all else has died. That the 

 individual portions of very young conceptuses undoubtedly have considerable 

 power of independent, though not necessarily post-mortem, growth is shown by 

 such specimens as No. 1843 (fig. 7, plate 1, Chap. IV), a conceptus in which the 

 chorion and yolk-sac have reached a considerable size, although the embryo and 

 amnion both are absent, except perhaps in the merest rudiments, as shown in figure 

 172 (plate 16, Chap. XI). However, it is highly probable that this power of 

 independent growth is far greater before than after the time when the fetal circu- 

 lation has become established in the cyema and chorion. Soon after this time cessa- 

 tion of the embryonic circulation necessarily would seem to interfere effectively with 

 growth of the cyema and increasingly with the nutrition of the chorion and more 

 indirectly also with that of the amnion. However, before the fetal circulation 

 has been established, it is highly probable that even the embryonic disk may be 

 much more resistant to inhospitable surroundings, and one could pronounce these 

 very young conceptuses dead only after correlated cellular proliferation had ceased 

 entirely. 



Although the chorions of older specimens may die a more gradual death than 

 the cyema, one scarcely would expect any villi to be formed anew after the 

 death of the latter. The syncytium and trophoblast, however, both might con- 



