384 Fertilization and Early Development of Pigeon's Egg 



ViKCHOw, H., 97. — Ueber Unterschiede im Syncitium der Selachier Nach Ort. 



Zeit und Genus. Sitz. d. Ges. Naturf. Freunde zu Berlin, No. 7. 

 • 97. — Dotter Syncitium, Keimhautrand und Beziehungen zur Konkres- 



cenzlehre. Ergebn. d. Anat. u. Entwickelungsgesch. 

 Whitman, C. O., 87. — The Kinetic Phenomena of the Egg during Maturation 



and Fecundation. Jour, of Morph., I, 2. 



88. — The Seat of Formative and Regenerative Energy. Ibid., II. 



ZiEGLER, H. B., u. ZiEGLEK, F., 92. — Beitrage zur Entwickelungsgeschichte von 



Torpedo. Arch. f. Mikr. Anat., Bd. XXXIX. 

 ZiEGLER, H. E., 94.— Ueber das Verhalten der Kerne im Dotter der Meroblast- 



ischen Wirbeltiere. Ber. d. Naturf. Ges. Freiburg, i. B., Bd. VIII. 

 Hull Zoological Laboratory. 

 University of Chicago, 1902. 



EXPLANATION OF PLATES. 

 Plate I. 



Fig. 1. Ovarian egg 1.4 mm. in diameter, showing nucleus, x 120. 



Figs, la and b. Nuclei of ovarian eggs about 1 mm. in diameter, x ^12. 



Fig. 2a. Nucleus of ovarian egg 4 mm. in diameter, x 120. 



Fig. 2b. Horizontal section through germinal disc of ovarian egg, 14 inch 

 \n diameter, showing nucleus; a, group of chromosomes; 6, chromatin network. 

 X 120. 



Fig. 3. Nucleus of an ovarian egg % of an inch in diameter, x 120. 



Fig. 4a. Vertical section through germinal disc and nucleus of ovarian egg, 

 % of an inch in diameter. X 50. 



Fig. 4b. Nucleus of same, enlarged; a, group of chromosomes; 6, group of 

 nucleoli; c, refractive substance; d, wall of nucleus; e, follicular envelope of 

 egg, outer layers of capsular wall not shown. Combination of two sections. 

 X 385. 



Fig. 5. Vertical section through disc of mature ovarian qse, taken from 

 ovary after laying of first egg. Time, 7.30 P.M.; a, spindle; B, perivitelline 

 layer; c, layer of substance free from deutoplasmic granules, x 200. 



Plate II. 



Fig. 6. Surface appearance of germinal disc about time of fertilization; a, 

 inner area; 6, outer zone; c, fovea, x 10- 



Fig. 6a. Horizontal section of germinal disc of egg loosed from ovary and 

 not yet entered oviduct. Time, 9.00 P.M.; a, egg nucleus; b, sperm nuclei; 

 c, polar ring, x 125. 



Fig. 6b. Same enlarged, showing zone in which the sperm nuclei lie. 

 X 1000. 



Figs. 7a-h. Stages in transformation of entering sperms, x 2000. 



Fig. 7i. Inwandering follicular cell, x 2000. 



Fig. 8. Vertical section through disc showing second polar spindle, polar 

 body and surroundings. Combination of two sections. Position In upper end 

 of oviduct. Time, 7.45 P. M. x 200. 



Fig. 9. Vertical section, showing second polar spindle, polar body and 

 surroundings. Time, 10.15 P. M. X 333. 



