344 HYDATIFORM DEGENERATION IN TUBAL AND UTERINE PREGNANCY. 



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. 



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

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

 in the first 1,187 accessions, then we get over 314 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 examined 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 somewhat, 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 the Mall 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 thousands also must be 

 taken into consideration. But in any case the estimated incidence of hydatiform 

 degeneration in the Mall Collection, calculated without regard to those contained 

 among specimens classed as normal, is 7.5 per cent, and the actual incidence hence 

 probably is more than 1 in every 10 accessions. The incidence among the uterine 

 specimens alone would be 10.9 per cent, and among the tubal alone 20.8 per cent. 

 This difference of 100 per cent between the tubal and uterine specimens may have 

 a probable significance in connection with the cause of hydatiform degeneration. 



If, as alleged by various investigators, the great majority of abortions occur 

 in the first 3 months, it is highly probable that many of these early conceptuses 

 are lost and never come to the attention of any one, and that therefore the pro- 

 portion of early specimens in this or any other collection is no doubt too small. 

 Moreover, in quite a number of specimens of the first 1,000 accessions the chorionic 

 vesicles were too degenerate for examination, and in others they were absent, but 

 we have reason to believe that this is not true to the same extent in the material 

 beyond the first 1,000 accessions. Then, too, since only a few relatively large 

 sections from a single portion of the chorionic vesicles were examined, it is evident 

 that some cases in which the degeneration may have been purely local probably 

 were overlooked. Hence the actual incidence of hydatiform degeneration in this 

 collection is probably not merely 8 times but 240 times as great as that given by 

 Williamson (1900), and 33.3 times as great as that given by Essen-Moller. 



Most persons will, I presume, be willing to regard an increase of 700 per cent 

 above that of Williamson as possible, but one of 24,000 per cent above Williamson, 

 or even 3,333 per cent above that of Essen-Moller as wholly out of the question. 



