No. 1.] ORIGIN OF HUMAN MONSTERS. 63 
the cylindrical form in four, and are necrotic and disinte- 
grating in the remaining specimens. In general, the changes 
in the chorion and embryo in these 14 specimens are the same 
as in those that are obtained from uterine pregnancies. It 
cannot possibly be admitted that the primary difficulty in 
these specimens is to be found in the embryo itself, that is, it 
is germinal, for the ova which become lodged in the tube are 
probably of an average kind, unless the unreasonable stand 
is taken that there is a greater tendency for abnormal than 
normal ova to lodge in the tube. To take this stand it is 
necessary to overlook altogether those cases in which tubal 
pregnancy is due to mechanical obstruction of, or to diverticula. 
from the uterine tubes. The results obtained from the study 
of these 14 specimens are probably representative of all tubal 
pregnancies which are examined with great care before the 
tubes rupture. In the very earliest specimens there are indi- 
cations of faulty implantation, due no doubt to the character 
of the tissue of the tube which permits of an excessive hemor- 
rhage around the ovum (e. g., No. 396). Only in rare 
instances does a good decidua form in the tube, which in 
these cases must be produced by the presence of a growing 
ovum. However, just in these cases a decidua develops in 
the uterus, although the ovum is not present there. 
I have found in collecting 434 human embryos of all kinds 
that 163 of them, or 38 per cent., are pathological. If we 
consider that an abortion occurs in every fifth pregnancy, then 
a pathological ovum is found in every twelfth pregnancy (7 
per cent in the table). If anything, this number is too high, 
for a number of larger normal fcetuses were not catalogued 
and are not included with the total number—434. If the 
data obtained -from unruptured tubal pregnancies where the 
number of pathological specimens rises to 96 per cent are 
compared with the pathological specimens from uterine preg- 
nancies (7 per cent), it seems to me that the argument against 
the germinal origin of pathological ova and monsters is over- 
whelming. 
The relation of the chorion to the wall of the tube or to 
the mucous membrane of the uterus is well known for ova 
