210 STUDIES ON PATHOLOGIC OVA. 



degeneration given in the records of the Carnegie Collection is based upon deter- 

 minations made essentially in the usual way that is, by unaided inspection of the 

 gross specimen alone we must regard it also merely as an apparent, not as the 

 actual, incidence. For, as will appear later, the actual incidence can be revealed 

 only by a careful gross and microscopic study of all specimens, both normal and 

 pathologic. Such a study has not as yet been completed, but 348 uterine specimens 

 classed as pathologic, and 108 pathologic tubal specimens, contained in the first 

 1,200 accessions, were carefully examined. 



The actual number of cases of hydatiform degeneration found among the 

 333 chorionic vesicles of uterine abortuses classed as pathologic in the first 1,200 

 accessions was 105, or 31.5 per cent of the whole. This includes some doubtful 

 cases, but a revision probably would add more than it would exclude. The inci- 

 dence of hydatiform degeneration in the pathologic tubal pregnancies was some- 

 what higher even, or 45 specimens of undoubted hydatiform degeneration out of 

 108, or 41.7 per cent. Since nearly all the tubal specimens are young, while the 

 uterine series contains many more relatively older ones, the effect of this fact upon 

 the determined relative incidence of hydatiform degeneration among the patho- 

 logic tubal and uterine specimens must be borne in mind. For a reliable conclusion 

 regarding the relative incidence in the uterine and tubal pregnancies it would be 

 necessary to select a series from each, composed of specimens of approximately 

 corresponding ages. What the incidence of hydatiform degeneration is among the 

 uterine and tubal specimens classed as normal I do not know, but it undoubtedly 

 is far below that in those classed as pathologic. It is well to remember, however, 

 that many, if not most, of the instances of beginning degeneration very likely will 

 be found among the specimens classed as normal. This is well illustrated by a 

 hysterectomy specimen, No. 836, represented in figures 96 and 97. 



If we assume that the incidence of hydatiform degeneration among the patho- 

 logic specimens in the rest of the Carnegie Collection is the same as that among 

 those in the first 1,200 accessions, then we get over 375 estimated instances of 

 hydatiform degeneration in pathologic tubal and uterine cases alone. Since I have 

 found a number of chorionic vesicles accompanying embryos classed as normal 

 which also show hydatiform degeneration, this number would be increased still 

 further; but unfortunately too few of the specimens classed as normal were ex- 

 amined to justify an estimate. Yet these normal specimens form 60.4 per cent of 

 the first 1,000 and 40.7 per cent of the first 2,500 accessions. This supposed increase, 

 due to inclusion of specimens contained among the normal, would be offset some- 

 what, however, by the fact that the first 1,000 accessions contain a somewhat 

 larger proportion of young conceptuses, each succeeding 1,000 probably becoming 

 somewhat more representative of actual life conditions. The difference between 

 the composition of the first 1,000 accessions and that of the 1,000 between 1,500 

 and 2,500 is not very great, however, for the former contains only an excess of 

 17.6 per cent of cases falling in the first five groups of Mall's classification, which 

 groups are composed largely of specimens below an embryonic length of 20 mm. 

 Then, the relative proportions of tubal and uterine specimens in the different thou- 



