THE GENESIS OF THE EGG Ii\ TRITON. 26S 



The wall of the ovary (fi^. 1) consists of three layers — 

 an external germinal epithelium {g. ep.), a linimj epithelium 

 [1. ep.), and a middle layer of connective tissue or stroyna 



The cells of the ger?ntnal epithelium, seen from the surface 

 ■with a magnifying power of 400 to 500 diameters, generally 

 shoAv smooth hexagonal boundaries^ with nuclei (n.) lying 

 near the centre, or, more commonly, towards one side of the 

 cell. 



The nuclei have a somewhat elongated oval form, the 

 shorter axis measuring about '016 mm., the longer about 

 •023 mm. 



By lowering the focus the nuclei of the stroma (st. n.) are 

 brought into view, together with fine blood-vessels, which 

 traverse the stroma. In this layer no cell boundaries can 

 be recognised. The nuclei are easily distinguished from 

 those of the superficial epithelium, being smaller ("010 by 

 •013 mm.), sharper in outline, and elliptical in shape. 



Placing the focus still lower, the elongated polygonal 

 cells of the lining epithelium {I. ep.) are seen. These cells 

 are bounded by fine wavy lines; the nuclei {I. n.) have an 

 elongated oval or elliptical form, and are a little larger 

 than those of the germinal epithelium, measuring '017 by 

 •024 mm. 



The size of the cells of the germinal epithelium varies 

 from place to place, being much smaller in those areas 

 where primordial ova are forming than elsewhere. This 

 fact may be taken as an evidence that the epithelial cells 

 multiply by division, and that this multiplication is more or 

 less restricted to scattered patches or areas. 



Waldeyer (4) speaks of " cell-islands," or scattered aggre- 

 gations of pavement epithelial cells. In most cases he found 

 these cell-clusters lying beneath the germinal epithelium ;- 

 but in a few cases (see his fig. 28) some of these cells were 

 found to have a superficial position, the germinal epithelium 

 (endothelium) being absent in such spots. ^ I have made a 

 great many surface preparations, but I have never been able 

 to find any places where the continuity of the germinal 

 epithelium was broken. 



If my view of the origin of the ova be correct, it would be 

 difficult to account for such a break in the outer layer as 

 Waldeyer has described and figured, except by supposing 

 that the preparation itself was faulty. Waldeyer's figure 



1 Waldeyer's opinion that the outer layer of the wall of the ovary is nof 

 epithelium, but peritoneal endothelium, rest upon a distinction that finds no 

 support in the latest investigations on the origin of the peritoneum. 



