104 STUDIES ON PATHOLOGIC OVA. 



are composed of villi only and of empty whole or of fragmented chorionic vesi- 

 cles. This leaves only 27 per cent to be distributed among the other five groups 

 of the pathologic division. Furthermore, the preponderance of the specimens fall- 

 ing into the first two groups actually is even more pronounced than this, for not 

 a single tubal specimen formed of villi only is included among the accessions below 

 No. 415. This is due mainly to the fact that Fallopian tubes containing what 

 appeared to be blood-clot only were not retained in the earlier days of the col- 

 lection. 



If we assume that the incidence of specimens containing villi only was the 

 same among the first 400 as in the last 800 of the first 1,200 accessions, then the 

 total number of specimens composed of villi only rises from 39 to 78, and the per- 

 centage of those in the first two groups from 73 to 78. These percentages stand 

 in very marked contrast to those in uterine abortuses, in which specimens 

 composing the corresponding groups form only 18.4 per cent of all the. path- 

 ologic. Since all the specimens contained in these two groups necessarily are 

 young, and hence also relatively small, it is evident that it probably would be 

 incorrect to attribute to the unusual conditions within the tube this difference 

 between the relative number of the uterine and tubal specimens contained in the 

 first two groups. It would seem that the tube, although small, is sufficiently 

 large and sufficiently distensible to permit growth to proceed sufficiently actively 

 to assure development beyond the stage represented by the specimens composing 

 these two groups. Consequently, it seems that the death of the embryo, with 

 subsequent disintegration of it and of the surrounding amnion, and in almost half 

 of the cases also of the chorionic vesicle itself, must be due to other things than a 

 mere lack of space within the tube. Nor can the large percentage of young tubal 

 specimens be attributed solely to the diagnostic skill of the surgeon, for in this 

 case the chorionic vesicles falling into group 2 not only should contain an amnion 

 and an embryo, but the whole conceptus should still be in a splendid state of pres- 

 ervation. This, however, is not true of any of these specimens, not even in the 

 instance of twin tubal pregnancy already referred to, although in this case both 

 chorionic vesicles are still implanted within the tube-wall throughout the whole 

 area of contact. 



The high incidence of hydatiform degeneration, especially in these groups, as 

 well as the presence of infiltration of the wall of the tube, probably points directly 

 to the real cause for this difference, which very likely is to be found in the absence 

 of a nidus sufficiently favorable for implantation and growth. Nevertheless, 

 development within the tube must proceed under more unfavorable mechanical 

 conditions than within the uterus, for the latter probably undergoes expansion 

 more spontaneously, pari passu with the growth of the conceptus. The tube, on 

 the other hand, undoubtedly does not do so to the same degree, but becomes 

 distended while its walls are being eroded by the trophoblast. Consequently (as 

 so well illustrated in the case of No. 825, a twin tubal pregnancy), the tube, by 

 virtue of its elasticity alone, must subject the contained, growing conceptus to 

 considerable pressure. Nor is it only the elastic recoil of the tube-wall that the 



