86 MALL. [Vor. XIX. 
same story. In 310 the villi are of irregular length, their 
structure is hyaline with vacuoles, and they contain remnants 
of blood-vessels of the embryo. They are imbedded in a 
mass of fibrin and pus. 
In No. 20 the only change found is a considerable amount 
of granular matter between the villi, and in No. 190 there 
are no changes whatever; however, the villi contain blood- 
vessels. In specimen No. 255 it is again observed macroscopic- 
ally that the villi are atrophic, and sections show that the 
mesoderm is fibrous. In between the syncytial masses there 
are many leucocytes, which have invaded the villi and the 
mesoderm of the main wall of the chorion. 
Up to this time the ccelom contains reticular magma in 
most cases, but as the specimens grow larger and presumably 
older first granular magma is found mixed with the reticular 
and finally displaces it altogether. The last four ova of the 
group under consideration (Nos. 29, 195, 243 and 358) are 
each 30 mm. in diameter, may be fully four weeks old, and are 
beginning to take on secondary changes. No 29 is filled with 
granular magma, the mesoderm of the chorion and its villi 
are fibrous and being invaded by the syncytial cells. The 
whole is encapsulated in a layer of mucus, in which there are 
numerous leucocytes. No. 195 shows no changes in the 
chorion, which, however, contains blood-vessels. Extreme 
changes have taken place in No. 243. It is an irregular, 
collapsed, pear-shaped chorion, showing the beginning of a 
solid mole. Sections of No. 358 show that the villi are matted 
together, much blood and syncytium being between them, and 
they are encircled by a fibrous syncytium rich in leucocytes. 
Up to this time the changes in the chorion are quite equally 
distributed over its walls, and a change found on one part of 
it is also found on the other. However, the impaired nutri- 
tion may influence villi which stand side by side, some becoin- 
ing smaller and disappearing while others are becoming hyper- 
trophic. In fact, one of the best signs of the abnormality of 
an ovum before it is opened is this inequality of its villi. 
However, when an ovum is collapsed the story is entirely 
