EXPLANATION OF PLATES 27, 2t 



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

 pighian bodies. • 



Fig. 35' Transverse section tlirough 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 {(.), 

 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. 



f^ig- 35 ■*• Transverse section through a small part of the ovary of an embryo 

 from the same female as fig. 35, hardened in picric acid, shewing the relation of the 

 germinal epithelium to the subjacent tissue. Zeiss D D, ocul. 2. 



F'g- 35 5- Longitudinal section through part of the Wolffian body and the ante- 

 rior end of the ovary of an eighteen days' embryo, to shew the derivation of tubu- 

 liferous tissue (/.) from the Malpighian bodies, close to the anterior extremity of the 

 ovary. Zeiss A, ocul. i. 



Fig. 36. Transverse section through the ovary of an embryo rabbit of twenty- 

 two days, hardened in osmic acid. It is coloured in the same manner as fig. 35. 

 Zeiss A, ocul. 2. 



Fig. 36 A. Transverse section through a small part of the ovary of an embryo, 

 from the same female as fig. 36, hardened in picric acid, shewing the relation of tlie 

 germinal epithelium to the stroma of the ovary. Zeiss D D, ocul. 2. 



Figs. 37 and 37 A. The same parts of an ovary of a twenty-eight days' embryo as 

 figs. 36 and 36 A of a twenty-two days' embryo. 



Fig. 38. Ovary of a rabbit five days after birth, coloured in the same manner as 

 figs- 35. 36 and 37, but represented on a somewhat smaller scale. Ficric acid. 



Fig. 38 A. Vertical section through a small part of the surface of the same ovary 

 as fig. 38. Zeiss D D, ocul. 2. 



Fig. 38 B. Small portion of the deeper layer of the germinal epithelium of the 

 same ovary as fig. 38. The figure shews the commencing difi'erentiation of the cells 

 of the germinal epithelium into trtie ova and follicle cells. Zeiss DD, ocul. 2. 



fig- 39 A. Section through a smaU part of the middle region of the germinal 

 epithelium of a rabbit seven days after birth. Zei.ss D D, ocul. 2. 



Fig. 39 B. Section through a small part of the innermost layer of the germinal 

 epithelium of a rabbit seven days after birth, shewmg the formation of Graafian folli- 

 cles. Zeiss D D, ocul. 2. 



Figs. 40 A and 40 B. Small portions of the middle region of the germinal epithe- 

 lium of a rabbit four weeks after birth. Zeiss D D, ocul. 2. 



Fig. 41. Graafian follicle with two ova, about to divide into two follicles, from a 

 rabbit six weeks after birth. Zeiss D D, ocul. 2. 



EXPLANATION OF PLATES 27 AND 28. (XIII. p. 618.) 



Complete List of Reference Letters. 



ao. Aorta, cv. Cardinal vein. gl. Glomerulus, gr^ First groove of head- 

 kidney. gr„. Second groove of head-kidney, gr^. Third groove of he.id-kidney. 



