MATURATION AND FECUNDATION OF THE OVUM. 135 
Fig. 11. — Same stage, showing achromatic part of the nuclear structure. 
Same method. (V. B., PI. XIX ter, fig. 3.) 
Fig. 12. — Later stage. (V. B., PI. XIX ter, fig. 10.) 
Fig. 13.— Edification of the daughter nuclei. (V. B., PI. XIX ter , fig. 13.) 
Fig. 14. — Ovum of Nephelis three quarters of an hour after deposition. 
Formation of first polar globule. Acetic acid, 1 per cent, glycerine. Zeiss, 
f, oc. 2. (0. Hertwig, ‘ Morph. Jahrb.,’ Bd. iii, PI. ii, fig. 3.) 
Fig. 15. — Formation of “Amphiaster de rebut” in ovum of Asterias 
glacialis. No. Germinal vesicle, no. Germinal spot. Ar 1 . Amphiaster de 
rebut. V. Vitellus. Picric acid, glycerine. 400 diam. (Fol, ‘ Comm, de 
l’Henogenie,’ PI. ii, fig. 3.) 
Fig. 16. — Formation of “Amphiaster de rebut” iu ovum of Pterotrachea. 
Acetic acid, glycerine with alcohol. 400 diam. F. Central. F'. Peripheral 
fibrils of forming spindle, f. External rays of polar sun. a. Centre of polar 
sun. Nov. Envelope of germinal vesicle. V. Vitellus. (Fol, ibidem, PI. vii, 
fig. 14.) 
Fig. 17- — Formation of first polar globule in Pterotrachea. Acetic acid, 
glycerine, at. Aster interne. Cr 1 . Corpuscle de rebut. Fc. Chromatin granules. 
Ar'. Chromatin left in ovum. Eo. Envelope. (Fol, ibidem, PI. viii, fig. 5.) 
Fig. 18. — Origin of directive spindle in ovum of Asteracanthion. Osmic 
acid, picro-carmine. Thirty minutes after deposition. (O. Hertwig, ‘ Morph. 
Jahrb.,’ Bd. iv, PI. viii, fig. 1.) 
Fig. 19. — Ovum of Asteracanthion, forty-five minutes after deposition. 
Acetic acid. (Ditto, ditto, fig. 3.) 
Fig. 20. — Ovum of Mytilus, immediately after deposition, a. Directive 
spindle, b. Residue of germinal vesicle. (Ditto, ditto, PL x, fig. 2.) 
Fig. 21. — Ovum of Ascaris megalocephala. Second directive spindle. 
K. Refringent body of spermatozoon. Sp. K. Head of spermatozoon. IRK. 
First polar globule. II. Rs. Second directive spindle. I. First. II. Second 
vitelline envelope. (Nussbaum, ‘Arch. f. Mik. Anat.,’ Bd. xxiii, PI. x, 
fig. 34.) 
Figs. 22 and 23. — Two spermatogemmae, each composed of four spermato- 
cytes and showing the cytophore in the centre in four pieces. Osmic acid, 
picro-carmine. (V. B., PI. XIX ter, figs. 19 and 20.) 
