436 MINOT. [Vou. II. 
to the margin of the placenta; at the same period the cellular 
layer forms a number of irregular patches over the chorion lzeve, 
while the protoplasmic layer remains over the entire surface, 
both where the cellular is present and where it is absent; the 
protoplasmic layer may undergo complete or partial degenera- 
tion into canalized fibrine, which is developed in irregular 
patches. The cellular layer remains on the villi only in a few 
patches (Ze//knoten) and over the tips of certain villi; the pro- 
toplasmic layer of the villi remains everywhere and develops 
numerous nodular thickenings; it changes partially into canal- 
ized fibrine. It is probable that the fibrine covering the surface 
of the decidua serotina is derived from the ectoderm of the ends 
of the villi imbedded in the decidua. The villi are at first of 
awkward and irregular forms, but their branching gradually 
becomes more regular, and the twigs acquire a slender and 
more uniform shape. 
§ 16. The menstruating uterus is characterized by hyperzemia, 
by hyperplasia of the connective tissue of the mucosa, and by 
hypertrophy of the uterine glands; the upper fourth of the 
mucosa is loosened and breaks off: there are no decidual cells. 
§ 17. The uterus one month pregnant has lost its epithelium 
from its surface, and from the ducts of its glands; owing to the 
dilatation and contortion of the deep parts of the glands, it is 
divided into a lower cavernous or spongy layer and an upper 
compact layer; the connective tissue of the upper layer is 
transformed into decidual cells; in sections the glands of the 
lower layer appear as crowded areolz, which are lined by a 
cylinder epithelium more or less disintegrated, or else filled 
with isolated enlarged epithelial cells. 
§ 18. The uterus seven months pregnant is without epithe- 
lium either on its surface or in the glands, except a few isolated 
patches in the deep parts of the latter; there is no trace of the 
decidua reflexa; the decidua vera is covered by the epithelium 
of the adherent chorion leve; the decidual serotina is covered 
for the most part bya layer of fibrine, which is probably derived 
from the degeneration of the chorionic ectoderm covering the 
imbedded ends of the villi; the decidua is divisible into an 
upper compact and a lower cavernous layer, in which latter the 
gland cavities are reduced to slits; the decidual cells are very 
numerous and crowded ; the larger ones lie near the chorion ; 
