126 J. r. HILL. 



vesiciilav nucleus ('05 X "03 mm. diameter) is situated, are clearly dis- 

 tinguishable. The zona (z. j)-) measm-es •0021-'0025 mm. in thickness. 

 Outside it are the follicular epithelial cells of the discus i^roligerus 

 {d. p.), which is thickened on the upper side of the figure, where it 

 hecomes continuous with the memln-ana granulosa. (D. v i v., 21 . vii . 

 '04, \"-. Hermann's fluid and ix-on-hsematoxylin.) 



Fig. 2. — Photo-micrograph ( x 150) of ripe ovarian ovum (in which 

 first polar body is separated and second polar spindle is present, though 

 neither is visil)le in figure), "29 x '23 mm. maximum diameter. FoUicle 

 l-i X 11 mm. diameter. The ovum exhibits an obvious polarity. 

 Deutoplasmic zone (d. z.) in upper hemisphere ; formative zone (/. z.) 

 forming lower. (D. v i v., li, 26 . vii . '02, ~^. Flemming's fluid iind 

 iron-hajmatoxylin.) 



Fig. 3. — Photo-micrograph ( X 150) of ripe ovarian ovum (-28 x '24 

 mm. diameter) with first polar body {p. hK) and second polar spindle. 

 First polar body, •026-03 x 01 mm. Second polar spindle, "OlS mm. 

 in length. (D. v i v., 14, 26 . vii . '02, ^3. Flemming's fluid and iron- 

 hsematoxylin.) 



Fig. 4. — Photo-micrograph ( x 256) of ovarian ovum in process of 

 growth ("pseudo-alveolar" stage). Ovum, 26 x "20 mm. diameter. 

 Zona, •0017--002 mm. in thickness. (D. v i v., 14, 26 . vii . "02, j|^. 

 Hermann, iron-ha;matoxylin.) 



Fig. 5. — Photo-micrograph ( X 1250) of peripheral region of ripe 

 ovarian ovum ('28 x "126 mm. diameter) with first polar spindle ('015 

 X '013 mm.). (D. v i v.. 23 . vii . "02, -±^. Ohlmacher's fluid, iron-hsema- 

 toxylin.) 



Fig. 6. — Photo-micrograph ( X 1250) of peripheral region of ripe 

 ovarian ovum ('26 x "18 mm.), showing fii'st polar body (p. h\) ('03 X 

 '006 mm.). (D. v i v., 14, 26 . vii . '02, ^. Flemming, iron-hajmatoxylin.) 



Fig. 7. — Photomicrograph ( X 1250) of peripheral region of ovum, fig. 

 3, showing portion of first polar body {}}■ />'.), and the second polar 

 spindle. The dark body lying between p. bK and the surface of the 

 ovum is a displaced red blood-corpuscle. 



Figs. 8 and 9. — Photo-micrographs ( X about 84) of unsegmented ova, 

 respectively "33 mm. and '35 mm. in diameter, from the uterus, tiiken 

 immediately after their transference to the fixing fluid (picro-nitro- 

 osmic acid), showing the shell-membrane (.s. «i.), laminated albumen 

 (alb.), with sperms (sp.), the zona (z. p.), perivitelline space (p. s.), and 

 the body of the ovum, with its formative (/. z.), and deutoplasmic {d. z.) 

 zones. (D. v i v., 15, 19 . vii . '01.) 



Fig. 10.— Photo-micrograph ( X 150) of section of unsegmented ovum 

 almost immediately after its passage into the uterus, showing the very 



