6l6 THE STRUCTURE AND DEVELOPMENT 



Fig. 24. Fully formed ovum containing a second nucleus (x), probably about to 

 be employed as pabulum ; from the same ovary as fig. 5. The follicular epithelium is 

 much thicker on the side adjoining the stroma than on the upper side of the ovum. 

 Zeiss F, ocul. 2. Osmic acid. 



Fig. 25. A. Ovum from the same ovary as fig. 21, containing in the yolk three 

 peculiar bodies, similar in appearance to the two small bodies in the germinal vesicle. 

 B. Germinal vesicle of a large ovum from the same ovary, containing a body of a 

 strikingly similar appearance to those in the body of the ovum in A. Zeiss E, ocul. 2. 

 Picric acid. 



Fig. 26. Section of the ovary of a young female of Scy Ilium stellare i6 centime- 

 tres in length. The ovary is exceptional, on account of the large size of the stroma 

 ingrowths into the epithelium. Zeiss C, ocul. 2. Osmic acid. 



Fig. 27. Ovum of Scyllium canicula, 5 mm. in diameter, treated with osmic acid. 

 The figure illustrates the development of the yolk and a peculiar mode of prolifera- 

 tion of the germinal spots. Zeiss A, ocul. 2. 



Fig. 28. Small part of the follicular epithelium and egg membranes of a some- 

 what larger ovum of Scyllium canicula than fig. 22. Zeiss D D, ocul. 2. 



Fig. 29. The same parts as in fig. 28, from a still larger ovum. Zeiss D D, 

 ocul. 2. 



Fig. 30. Ovum of Raja with follicular epithelium. Zeiss C, ocul. 2. 



Fig. 31. Small portion of a larger ovum of Raja than fig. 30. Zeiss DD, 

 ocul. 2. 



Fig. 32. Follicular epithelium, &c., from an ovum of Raja still larger than fig. 31. 

 Zeiss D D, ocul. 2. 



Fig- 33- Surface view of follicular epithelium from an ovum of Raja of about the 

 same age as fig. 33. 



Fig- 34- Vertical section through the superficial part of an ovary of an adult Raja 

 to shew the relation of the pseudo-epithelium to the subjacent stroma. Zeiss D D, 

 ocul. 2. 



PLATE 26. 



COMPLETE LIST OF REFERENCE LETTERS. 



d o. Developing ovum. fc. Cells which will form the follicular epithelium, f e. 

 Follicular epithelium, g e. Germinal epithelium, mg. Malpighian body. n. Nest of 

 cells of the germinal epithelium, n d. Nuclei in the act of dividing, o. Permanent 

 ovum, o v. Ovary. / o. Primitive ovum. /. Tubuliferous tissue, derived from Mal- 

 pighian bodies. 



Fig. 35. Transverse section through the ovary of an embryo rabbit of eighteen 

 days, hardened in osmic acid. The colours employed are intended to render clear 

 the distinction between the germinal epithelium (ge.) and the tubuliferous tissue (tf, 

 which has grown in from the Wolffian body, and which gives rise in the male to parts 

 of the tubuli seminiferi. Zeiss A, ocul. 2. 



