RELATION OF VESICULAR MOLE TO CHORION CARCINOMA 161 
It would appear from all the sections I have examined, that it is essential, both 
for the normal growth and malignant proliferation of the syncytium, that it be in 
immediate contact with maternal blood. 
As shewn by Peters in his specimen, the trophoblast was intersected by blood 
spaces, communicating with the maternal sinuses, and on following the syncytium 
through all the stages of its existence, it is seen to be surrounded by maternal blood, 
not only normally in the placenta, but also in vesicular mole. Naturally, one would 
expect to find the same conditions existing in the malignant degeneration of the chorion, 
and they do, for in every place where syncytium is found, blood is also found in the 
immediate vicinity, not only in the primary focus, but also most markedly in the 
secondary deposits. 
The presence of the smaller more discrete cells of Langhams appears to 
be by no means constant. Whether this is due to the uneven rate of growth or 
to the variations in the general blood pressure is uncertain, but it is interesting to 
note that in a number of the recorded cases, only one variety of cell is mentioned 
as composing the growth, and that invariably the syncytium. 
This is another argument in favour of both cells having a common origin 
in the trophoblast, seeing that, at any stage of its existence, the latter may be con- 
verted into syncytial masses. 
Through the kindness of Dr. Hume, of Baltimore, I have had the privilege 
of studying sections of Whitridge Williams' specimen, and have found it to agree, 
both in the primary and secondary growths, with the appearances described in my 
second case. 
The first case supplies its own proof, since the connexion of the degenerated 
villi with the malignant tissue is actually observed under the microscope, the two 
varieties of cells being seen in situ not only attached to the villus, but pene- 
trating far and wide into the muscular coat and blood vessels of the uterus. 
It has been allowed by all those who have hitherto disbelieved in the foetal 
origin of this disease that, if it can be shewn that the elements comprising the 
tumour are chorionic, the required proof will be found in the study of vesicular 
mole. It is on these lines that I have tried to trace the life history of these cells, 
from the trophoblast of the ovum in its earliest stages to its later development, as seen 
in a fully-formed villus and in the benign and malignant growths found in vesicular 
mole and chorion carcinoma respectively. 
It has been objected by many English and American writers, that this 
condition should be regarded as a rapidly-growing sarcoma, developed during 
pregnancy, and shewing unusual changes due to the genetic influence of that 
state. 
While quite prepared to admit that such sarcomata may exist, and shew 
characteristic changes due to the influence of pregnancy, it has still to be proved 
w 
