OF THE VERTEBRATE OVARY. 555 



of Scyllium stellare, i6i centimetres in length, a section of 

 which is represented in PI. 25, fig. 26. In this ovary, although 

 no other abnormalities were observable, the stroma ingrowths 

 were exceptionally wide ; indeed, quite without a parallel in my 

 series of ovaries in this respect. The stroma most clearly 

 divides up the epithelium of the ovary into separate masses, or 

 more probably anastomosing columns, the equivalents of the 

 egg-tubes of Pfluger. These columns are formed of normal cells 

 of the germinal epithelium, which enclose ovarian nests and ova 

 in all stages of development. A comparison of the section I 

 have represented, with those from previous stages, appears to 

 me to demonstrate that the relation of the epithelium and 

 stroma has been caused by an ingrowth or penetration of the 

 stroma into the epithelium, and not by a mutual intergrovvth of 

 the two tissues. Although the ovary, of which fig. 26 represents 

 a section was from Scy. stellare, and the previous ovaries have 

 been from Scy. canicula, yet the thickness of the epithelium may 

 still be appealed to in confirmation of this view. In the previous 

 stage the thickness was about O'og6 mm., in the present one it 

 is about O'i6mm., a difference of thickness which can be easily 

 accounted for by the growth of the individual ova and the 

 additional tracts of stroma. A pseudo-epithelium is more or 

 less clearly formed, but it is continuous with the columns of 

 epithelium. In the stroma many isolated cells are present, 

 which appear to me, from a careful comparison of a series of 

 sections, to belong to the germinal epithelium. 



The thickness of the follicular epithelium on the inner side 

 of the larger ova deserves to be noted. Its meaning is discussed 

 on p. 567. 



Quite a different interpretation to that which I have given 

 has been put by Ludwig and Semper upon the parts of the 

 ovary at this stage. My pseudo-epithelium is regarded by them 

 as forming, together with the follicular epithelium of the ova, the 

 sole remnant of the original germinal epithelium; and the masses 

 of cells below the pseudo-epithelium, which I have attempted to 

 shew are derived from the original germinal epithelium, aie 

 regarded as parts of the ingrowths of the adjacent stroma. 



Ludwig has assumed this interpretation without having had 

 an opportunity of working out the development of the parts, but 



362 



