346 HYDATIFORM DEGENERATION IN TUBAL AND UTERINE PREGNANCY. 



degeneration in all gestations would then be 1 in 10, as based upon Pearson's, and 1 in 

 25, as based upon Mall's estimated prenatal mortality. But even if, as estimated 

 upon this basis, 4 or 10 per cent of all conceptions end in hydatiform degeneration, 

 this does not necessarily contradict the current opinion regarding its rareness at or 

 near term. 



A careful examination with the binocular microscope of all specimens has shown 

 that hydatiform degeneration as a rule is sufficiently general even in young vesicles, 

 so that sections of a single portion about 10 mm. square, would enable one to make 

 a fairly reliable diagnosis. Now and then, however, the process seems to be rather 

 irregularly developed, especially in the larger specimens. 



In order to determine accurately the question of distribution of hydatiform 

 degeneration over various portions of the chorionic vesicle, it will be necessary to 

 examine a series of sections of portions of the chorionic vesicle for each small 

 specimen. This has not yet been done, but since the portions used for microscopic 

 examination had been taken at random without previous knowledge of the existence 

 of hydatiform degeneration in any but the 8 specimens above described, and since 

 a series of 453 vesicles was examined, I can not believe that it can often be limited 

 to any particular area on relatively young vesicles. In these it usually is universal 

 even if not complete. It is of special interest in this connection that Muggia (1915), 

 after reviewing the small list of cases of alleged hydatiform degeneration of the 

 chorion laeve in connection with a study of a case of his own, came to the conclusion 

 that these cases are not really degenerations of the chorion laeve, but merely partial 

 degenerations of the placenta. Although I have given no thorough attention to 

 the normal changes in the chorion lacve, I am quite certain that they are not the 

 cause of confusion in the series of hydatiform degenerations from the Mall Collec- 

 tion. Cases in which whole chorionic vesicles exquisitely hydatiform in character 

 were contained in the tubes, and a number of others which still were implanted 

 within the uteri showed equally exquisite hydatiform changes around the whole 

 perimeter. Such cases as these ultimately confirm the opinion that in young vesicles 

 as a rule the condition is general except at its very inception. This is true 

 particularly by the time the degeneration has reached a stage which can be con- 

 sidered at all typical in its gross development, as determined by careful examina- 

 tion of numerous specimens with the binocular. 



It is especially interesting that, just as soon as typical hydatid elliptical villi, 

 or portions of the same begin to appear, the condition can be recognized with some 

 certainty under a magnification of 12 to 20 diameters with the binocular micro- 

 scope. It often was surprising how relatively early stages could thus be detected 

 and the diagnosis confirmed later by histologic examination. Indeed, celloidin 

 blocks of tissue from which sections had been cut gave splendid testimony when 

 examined in fluid with the binocular. One of the not very early stages contained in 

 utero and represented in figure 16 could be recognized with the unaided eye; and 

 when examined with the binocular, under a magnification of about 12 diameters, 

 the picture was unusually fine and wholly unmistakable, as shown in figure 17. 



