OVARY AND OVARIAN OVA IN CERTAIN MARINE FISHES. 115 



which it started when the egg first began to develop — namely, 

 that of a portion of the superficial tissue of the germinal fold 

 or lamella. 



The opening of the follicle, however, soon closes up, and 

 the whole cavity disappears by the contraction of the walls. 

 In follicles from which the eggs have only recently escaped, a 

 somewhat indefinite cellular tissue is seen, containing numerous 

 round nuclei. The appearance of the collapsed follicles in a 

 newly-spent plaice, as seen under a low power, is shown in 

 fig. 17, PI. 3, while fig. 18 shows a single follicle of the 

 ovary of the grey gurnard more highly magnified. The 

 internal cellular tissue is detached from the inner surface of 

 the wall of the follicle, and presents a different appearance 

 from that of the wall itself. I think there can be little doubt 

 that this tissue is the remains of the follicular epithelium. 1 

 have not observed any indication in later stages of hypertrophy 

 or proliferation of this epithelium — in fact, it soon ceases to be 

 distinguishable. It has recently been maintained by J. Sobotta 

 that the corpus luteum of the mammalian ovary is produced 

 chiefly by the hypertrophy of the follicular epithelium, but this 

 conclusion, if correct, does not appear to me to apply to the 

 Teleostean ovary. 



The wall of the empty follicle has the same structure as the 

 outer layer of the stroma of the ovary, of which it forms part. 

 It consists of connective tissue, somewhat fibrous in appear- 

 ance, containing numerous nuclei, and furnished with blood- 

 vessels. In its final stages, the follicle forms merely a globular 

 projection inwards from the surface membrane of the ovarian 

 tissue. At this stage it is a solid mass, consisting of fibro- 

 cellular connective tissue, quite similar to that which forms 

 the wall of the follicle at the earlier stage. I have not 

 observed anything in its structure at the later stages which 

 appears to be derived from the follicular epithelium. 



The absorption of the empty follicles proceeds rather rapidly, 

 and all trace of them has disappeared in ovaries which have 

 begun to mature the ova for the next season. On July 15th 

 I killed at Plymouth a plaice 16 inches long, of which the 



