28 MALL. [VoL. XIX. 
100 give pathological ova of which but one-third give well 
formed embryo monsters, or two per cent of all pregnancies. 
The number of monsters which go on to full term is about .6 
per cent, and it is just this group which has escaped me. The 
embryo and foetal monsters form, therefore, 2.6 per cent of all 
pregnancies, or, in other words, three well-formed monsters 
are aborted in the early months of pregnancy for every one 
which goes on to the end of pregnancy. 
It is clear that those cases in which the embryo is markedly 
deformed or is absent altogether, as is the case in about 100 of 
my specimens, cannot possibly develop for any great length 
of time, for without either heart or form they cannot exist. 
However, the second group of forty-eight embryo monsters 
show within themselves such radical changes that they also 
could not have existed much longer. In nearly all of them the 
heart is markedly changed, is atrophic or is wanting altogether. 
There are also many other changes, especially in the central 
nervous system, which makes it probable that they have lived 
as long as they could and were then finally aborted. In 
general, I think that the form of the monsters and their clas- 
sification show clearly that they are practically identical 
with those that grow into foetuses and then to full term, differ- 
ing only in the degree of their changes. These are so radical 
in the embryo monsters that their lives are destroyed. 
Teratologists have long ago observed that the heart must 
be affected more or less in monsters on account of the fre- 
quent oedematous condition of the tissues and of the excessive 
accumulation of fluids in the serous cavities and in the 
amnion. In fact, a large per cent of monsters have hydro- 
cephalus and hydramnios. These conditions are seen in 
many of my specimens and have been observed by experi- 
mental teratologists like Panum and Dareste. However, 
we now have some good experiments which throw some light 
upon this subject. 
In 1893 Loeb* made the brilliant discovery that the heart 
beat could be arrested in Fundulus by placing the eggs in a 
“Loeb, Pfliiger’s Archiv, LIV, 1893. 
’ 
