THE VILLI IN ABORTUSES. 323 



ated but otherwise normal villous tree in figure 262, the branches of which bear 

 decidual masses and trophoblastic nodules. Nothing could stand in more marked 

 contrast to this and other normal villous trees than the excellent hydatiform villi 

 in figure 263, which were taken from a vesicle 40 by 36 by 18 mm., of approximately 

 the seventh week. This contrast is emphasized further by such normal specimens 

 as the villi from No. 837, shown in figure 264, transition forms between which and 

 the former are typified in the villi represented in figures 265 and 266, taken from 

 vesicles 45 by 35 by 30 mm. and 80 by 60 by 50 mm., respectively, the former of 

 which also shows maceration changes. 



Other types of normal villi from vesicles of the eighth week are shown in figure 

 267. In these villi from a vesicle 54 by 50 by 43 mm., as in some older specimens 

 to be referred to later, the most striking thing is the presence of many small knobs 

 on all sides of the branches. This is illustrated splendidly by the villous tree 

 shown in figure 268, which was taken from a placenta of the thirty-sixth week. 

 There seems to be a great variation in the occurrence of this knobbing which 

 probably does not signify beginning branching. The knobs are too numerous for 

 this when they are at all well developed, and, since they are so uniform in size, one 

 would have to think of a perfect shower of branches arising at the same time. 

 Since the placentse in which knobbing of the villi was especially evident look abso- 

 lutely normal, I have come to regard its presence as tj^pical for villi beyond a certain 

 age, without, however, regarding those in which it is present only in a minor degree 

 as necessarily pathologic. A villous tree in which sparse knobbing is evident only 

 upon magnification is that shown in figure 269, in which rather miscellaneous 

 branching is present. Other filiform villi, and a group of them from this placenta 

 of the eighth to ninth week, are shown in figure 270. 



What a contrast in external appearance villi from different placentse may show 

 is illustrated in figures 271 to 278, villi of the eleventh, twelfth, fourteenth, fifteenth, 

 thirteenth, nineteenth, twenty-fourth, and twenty-fifth week, respectively. Nor 

 are these variations in the 'external appearance of the villi to be attributed to age 

 alone or necessarily to pathologic changes. The villi shown in figures 271, 272, 

 and 274 look hydropic because of maceration, and those in figure 272 are decidedly 

 fibrous and largely non-vascular. The chorionic membrane of this vesicle was 

 decidedly infiltrated. The villus shown in figure 277 is also macerated, and the 

 chorion likewise was infected, but the stroma in this case was edematous and had 

 disappeared completely in places. Not infrequently the blood-vessels can be 

 seen as fine white lines on the exterior of these macerated specimens. The villi 

 shown in figure 273 came from a vesicle which had also been retained a consider- 

 able period of time, and those shown in figure 275, though filiform and fibrous, with 

 nodules at the extremities, are also macerated. 



Villi of small caliber are encountered quite frequently in apparently normal 

 older placentae, but are especially common in the capsular region, at a time when 

 retrogression of the chorion laeve is taking place. The contrast in form of the 

 villi shown here is remarkable. Those in figure 278 appear like the leafless branches 

 of an oak hung with streamers of lichen. These strange appearances are due to 



