90 MALL. [Vor. XIX. 
PATHOLOGICAL Ova AND Moises CoNTAINING AN AMNION 
Witnh THE Empryo DESTROYED WHOLLY OR IN 
GREAT PART. 
Under the last headings specimens were described in which 
most or all of the embryonic mass was destroyed, leaving the 
chorion to outline the ccelom. Such specimens are numerous 
and no doubt give rise to most of the solid moles. All other 
specimens in which the embryo is destroyed are of necessity 
those in which the amnion is formed, sweeps through and 
obliterates the coelom in its development and lines the chorion. 
It is evident when these two groups of specimens are consid- 
ered that the first must arise from ova of the first month, for 
in them the amnion is small, and the second group, from older 
ova after the amnion has reached the chorion. 
In general, the older the embryo is when it begins to become 
pathological the more resistant it is, and it follows that the 
younger the specimen the more easily it is destroyed. Prob- 
ably this is the reason why an ovum without an embryo rarely 
contains an amnion. No matter how large the specimen may 
be, if the interior of the chorion is not lined by the amnion it 
is safe to say that the pathological changes in it began during 
the first month (probably during the first fortnight) of preg- 
nancy. In case the disease of the ovum, which is usually due 
to endometritis, begins during the second month of pregnancy 
or later, the amnion is well formed, usually continues to de- 
velop, and reaches the chorion. Ova of this sort, which con- 
stitute the major portion of my specimens, contain embryos 
more or less degenerated, and at best form vesicular moles 
with the remnants of embryos within them. In a few of 
them, however, the embryos are destroyed, leaving only the 
umbilical cords, and in two or three specimens they were also 
destroyed, leaving only the chorion and the amnion. 
In all of these ova the cavity of the amnion is retained, and 
they do not appear to develop into solid moles, but may con- 
tinue to grow on indefinitely like those of the group given in 
Table ITT. 
