No. 3.] UTERUS AND EMBRYO. 359 
distinct, and the protoplasm around each nucleus dense and 
finely granular ; now the cell outlines are hard to follow and the 
picture is confused by broader lines of hyaline matter, which is 
colored by the eosine; the nuclei are enlarged, the protoplasm 
is more coarsely and more irregularly granular, and somewhat 
vacuolated. The characteristics enumerated concord with the 
idea that degeneration is going on, —an idea suggested, also, as 
before stated, by the failure to find this part of the ectoderm in 
later stages. 
5°. The blood-vessels show increased hypertrophy of their 
epithelium, and the perivascular cells form two or three layers 
around them; they are especially remarkable for containing a 
very large number of multinucleate leucocytes and comparatively 
few red corpuscles. The excessive abundance of white globules 
continues up to the oldest stage I have examined (sixteenth 
day). The predominance of nucleated corpuscles causes the 
contents of the maternal vessels to resemble foetal blood when 
examined with a low power; with high magnifications the dif- 
ference is evident. To the foetal blood in the placenta we shall 
have to recur. 
§ 7. Uterus at eleven days and three hours. — Very great 
changes have taken place — so great that they cannot be under- 
stood completely until some of the intermediate phases are 
studied. Want of suitable material has hitherto prevented my 
doing this. At the present stage—the beginning of the 
twelfth day —the placenta is distinctly pedunculate, and there 
is consequently a circular cleft between its sides and the closely 
adjacent peri-placenta; in the middle of the placenta a deep 
fissure corresponds, of course, to the space between the two 
folds of the uterus, out of which the placenta is developed, and 
therefore runs lengthwise of the uterus. The allantois has ac- 
quired considerable size and is attached to the surface of the 
placenta, from which the ectoderm has disappeared. The 
glands of the placenta are very far degenerated and altered; in 
the sub-glandular zone the multinucleate cells have appeared, 
and in the outer zone the perivascular cells have increased so as 
to occupy nearly all the space between the vessels. In the peri- 
placental and ob-placental regions, the modifications are equally 
noteworthy. Such, in brief, are the more striking changes. 
Let us consider them with greater detail. 
