No. 1.] ORIGIN OF HUMAN MONSTERS. 127 
embryos. The changes in them are so radical that it is im- 
possible for but few of them to develop into monsters had 
they not been aborted. However, it is not difficult to imagine 
specimens in which the changes are not so extreme, that is, 
they are due to minor changes in the chorion, which may 
retard the development of a part of the embryo, and after- 
wards become corrected, thus favoring the growth of a dis- 
torted embryo into a merosomatous monster. In nearly all 
of these embryos there is a tendency for the liquor amnii to 
increase in quantity, a condition which must also be viewed 
as a secondary process, and, therefore, cannot be of funda- 
mental significance in the production of monsters. 
It is evident from the study of pathological ova that in 
order to complete the chain of evidence it will be necessary to 
study anew and with much greater care the membranes of 
embryos which appear to be normal, for in them we shall no 
doubt find the very earliest stages of monsters which could 
have existed and grown throughout pregnancy. The recent 
publication of Fischel, as well as the more careful study of 
some of my “normal” embryos (Nos. 6, 10, 11, 12 and 80), 
indicates that embryos of this kind will probably serve to 
clear up entirely the subject under discussion. 
EMBRYOS OF THE SEVENTH WEEK. 
In the seventh week, when some of the bones are ossified, 
the embryos have reached a stage in which interference with 
their nutrition does not shatter all of their tissues at once. 
The effect upon the central nervous system is still more pro- 
nounced than that upon the other tissues, and even at this late 
period the dissociated structures continued to grow in an 
irregular fashion. 
The number of specimens at this time is also greatly 
diminished, as is naturally expected, for the younger ova are 
attacked early by the infected mucous membrane of the 
uterus and few of them survive until the seventh week. It 
follows, then, that as gestation continues pathological ova are 
