No. 3.] UTERUS AND EMBRYO. 389 
Meola, 59, ascribes a much more complex structure to the 
amnion than his predecessors, in which he is followed by Viti, 
21. Both of these authors subdivide the mesodermic stratum 
into three layers: a lamina connetivale, next the ectoderm, a 
sostanza intermedia, and a membrana limttante. As to the his- 
tological details, Viti differs somewhat from Meola, but agrees 
with him in finding a histological distinction between the three 
layers enumerated. The extent to which I can distinguish three 
layers is indicated by the description of the mesoderm given 
above: I have been unable to find the marked structural dif- 
ferences affirmed by Viti. Viti’s paper is to be commended for 
its excellent historical reviews, particularly for his summary of 
the various theories as to the origin of the amniotic fluid. 
§ 15. Chorion.— The human chorion has been the object of 
greater misconception than perhaps any other organ of the 
body. Even at the present time there prevail numerous false 
conceptions concerning it, nor do I know of any text-book which 
gives a satisfactory or even tolerably correct account of its 
structure. This singular confusion is not due to deficiency of 
observations, for from the vast literature of the subject (by 
trusting the accurate observers, such as Coste, Farre, Kolliker, 
Turner, Langhans, Waldeyer, etc.), we may cull a fairly com- 
plete and exact history of the development of the chorion. But 
the literature of the chorion consists chiefly of papers of little 
value, and often remarkable for the gross crudeness of the ob- 
servations they record, and for the proofs they are of their 
author’s ignorance of other and better investigations. It ap- 
pears that the anatomists and physiologists, by a species of 
tacit understanding much to be regretted, have regarded the 
uterus and placenta outside of their province, and have left the 
investigation of the anatomy and functions of these organs to 
gynecologists and others, whose capacities have lain rather in 
the direction of medical practice than of original research, al- 
though among them are some notable exceptions. The major- 
ity of the practitioners who have written on the uterus and 
foetal appendages have done at least as much harm as good. It 
would be a sheer waste of time to subject this mass of literature 
to a critical revision in order to extract from it what little there 
may be of value. I have, however, read a large number of the 
articles, and studied those which seemed worthy of it. Upon 
