HYDATIFORM DEGENERATION IN UTERINE PREGNANCY. 213 



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 is 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 so recorded and above 

 described, and since over 450 vesicles were examined, I can not believe that it can 

 often be limited to any particular small area on relatively young vesicles. In these 

 it usually is quite general even if not complete. It is of special interest in this con- 

 nection that Muggia (1915), after reviewing the small list of cases of alleged 

 hydatiform degeneration of the chorion Iseve 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 Iseve, I 

 am quite certain that they are not the cause of confusion in the series of hydatiform 

 degenerations from the Carnegie Collection. 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 the condition is, as a rule, 

 general, except perhaps at its very inception. This is true particularly by the 

 time the degeneration has reached a stage which can be considered at all typical 

 in its gross development, as determined by careful examination 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 

 microscope. 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 testi- 

 mony when examined in fluid with the binocular. One of the not very early 

 stages contained in utero and represented in figure 98 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 99. 



That hydatiform degeneration is incomparably more common in the earlier 

 than in the later months of pregnancy, thus justifying the comparison made with 

 measles, is substantiated by statistics covering the material examined. From these 

 it is evident that, excepting cases of large hydatiform masses originally classed as 

 hydatiform degeneration from inspection of the gross specimens alone, practically 

 all of the specimens are relatively young. This is true especially of those from tubal 

 pregnancies, and we may hence regard it as established that hydatiform degenera- 



