420 R. S. CUNNINGHAM 
are gradations between the intestine, body-wall, diaphragm, 
omentum, and the spleen; the latter approaching the type of 
staining manifested by the ovary more closely than the others. 
These cells have in common the localization of the dye in a par- 
ticular part of the cytoplasm of the cell, and while there is no 
direct evidence that similarity in the storage of vital dyes repre- 
sents similarity in physiological function, yet it is permissible to 
consider such findings suggestive. The extension of such studies 
to species such as the frog would be helpful because there is 
evidence suggestive of a greater similarity between the general 
serosal lining cells and the germinal epithelium in these species. 
With regard to the second question concerning the relationship 
between the germinal epithelium and the internal structures of the 
ovary, a very large amount of work has been done. Elaborate re- 
views of the literature have been given by Firket, Coert, von 
Winiwarter, and others, and it is entirely unnecessary to repeat 
these here. In brief, it has been accepted by most workers that 
the medullary cords are downgrowths of the germinal epithelium, 
and many also believe the so-called cords of the second prolifera- 
tion are likewise derived from the germinal epithelium. The 
question about which most of the discussion has been centered 
is the relation which the germinal epithelium bears to the defin- 
itive ova. 
Waldeyer (’70) found large numbers of cells in the germinal 
epithelium which he interpreted as young germ-cells, and con- 
cluded that these cells were developed entirely from the cells 
of the ovarian envelope. This view has been supported in gen- 
eral by many workers, among whom are von Winiwarter (’01), 
von Winiwarter and Sainmont (’09), Sainmont (06), Lane- 
Claypon (’06), Gatenby (16), and von Berenberg Gossler (712). 
In this way a general school has been developed whose principal 
belief is the origin of the definitive ova either directly from the 
germinal epithelium or from the cellular cords which have been 
developed as downgrowths from this superficial layer of cells. 
On the other hand, Rubaschkin (’07, 712) and Swift (14) 
have strongly supported the theory, advanced by Nussbaum 
(80, ’01), that the primordial germ-cells do not originate in the 
germinal epithelium, but come from cells which have not given 
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