THE DEVELOPMENT OF THE MOLE. 173 
19. E. A. Scnirer.—‘On the Structure of the Immature Ovarian Ovum in 
the Fowl and Rabbit,” &c., ‘Proceedings of the Royal Society,’ xxx, 
1880. 
20. Kart Scuvrtiw.— Zur Morphologie des Ovariums,” ‘ Archiv fiir Mikros- 
kopische Anatomie,’ xix, 1881. 
21. D. von Srnren.— Beitriige zur Frage nach d. Mikropyle d. Saugethiere,” 
‘Archiv fiir Anatomie und Physiologie,’ pt. i, 1882. 
22. H. Vircnow.—-“ Durchtreten von Granulozen-Zellen durch die Zona- 
pellucida des Siugethiereies,” ‘ Archiv fiir Mikroskopische Anatomie,’ 
xxiv, 1884. 
EXPLANATION OF PLATE XI, 
Illustrating Mr. W. Heape’s Paper on ‘‘ The Development of 
the Mole (Talpa Europea), the Ovarian Ovum, and 
Segmentation of the Ovum.” 
Reference Letters. 
e.v. s. Circum-vitelline space. fe. Follicular epithelium. fp. Female 
pronucleus. g. Granules within nucleus. m.c. Mucous coat. m.p. Male 
pronucleus. 2. Nucleus. zc. Nucleolus. y. 4. Polar body. 7. ¢. Radial 
canals. sp. Spermatozoa. v. m. Vitelline membrane. y. Yolk. z. Zona 
radiata. 
All the figures are drawings of the ova of the mole, except Fig. 21, which 
represents a guinea-pig’s ovum. Figs. 13—19 have been copied for me by Mr. 
H. A. Chapman. 
Fie. 1.—Ovarian ovum not yet ripe, surrounded by follicular epithelial 
cells, f. ¢. The outline of these cells is to be seen through the transparent 
zona, z. The outer edge of the zona is granular. A vitelline membrane may 
be distinguished here and there. (Zeiss D, occ. 2.) 
Fic. 2.—A ripe ovarian ovum. A few follicular epithelial cells only remain 
attached to the zona. Network of protoplasm permeating the vitellus. 
(Zeiss D, occ. 2.) 
Fies. 3, 4, and 5.—Nuclei of three mature ovarian ova, similar to that 
drawn in Fig. 2. Single nucleolus, ze., and large and small granules, v., in 
each nucleus. Yolk vesicles, y., and granules surrounding nucleus in Fig, 4. 
(Zeiss F, occ. 2.) 
Fic. 6.—A portion of the circumference of ovum represented in Fig. 2, 
VOL. XXVI.——NEW SER, N 
