208 ADAM SEDGWICK. 
ll. Kizty, E.—‘Glandular Epithelium and Division of Nuclei,” ‘ Quart. 
Journ. Mier. Sci.,? vol. xix. 
12. Leypie, F.—‘ Zelle u. Gewebe,’ Bonn, 1885. 
13. Mosrtey, H. N.—‘On the Structure and Development of Peripatus 
capensis,” ‘Phil. Trans.,’ vol. clxiv, 1874. 
14. Pritzner, W.—“Zur Morphologischen Bedeutung des Zellkerns,” 
‘Morph. Jahrbuch,’ Bd. xi. 
15. SrraspurceR, H.—‘‘ Die Controversen der indirecten Kerntheilung,” 
* Arch. f. Mic. Anat.,’ Bd. xxiii. 
16. Srricker, 8.—‘ Beobachtungen iib. d. Entstehung des Zellkerns,” ‘ Sitz- 
ungsb. d. k. Akad. d. Wiss.,’ June, 1877. 
DESCRIPTION OF PLATES XII, XIII, & XIV, 
Illustrating Mr. Adam Sedgwick’s paper on the “ Development 
of the Cape Species of Peripatus, the Segmentation of the 
Ovum, and Formation of the Layers.” 
List of Reference Letters. 
p. 6.,. First polar body. p. 6... Second polar body. £2. Female pronu- 
cleus. m.. Male pronucleus. 0. c. Cavity in centre of ovum. ss. d. More. 
deeply-staining bodies in extra-nuclear part of ovum. ec. Ectoderm. ez, En- 
doderm. e.s. Egg-shell. x. Network. w.e¢. Uterine epithelium. 4/. Blas- 
topore. g.g. Gut of gastrula. p.a. Polar area. yp. g. Primitive groove. 
p. st. Primitive streak. m. 6. Mesoblastic band. 
Fic. 1.—Section through the fertilised ovum of Peripatus Balfouri 
before the conjugation of the male and female pronuclei. The female pro- 
nucleus is at the periphery of the ovum. Its reticulum is very loose. Large 
masses of deeply-staining matter are present. The extra-nuclear reticulum is 
not denser round either the male or female pronuclei than elsewhere. A large 
cavity is present in the centre of the ovum. The extra-nuclear reticulum is 
only drawn in immediately round the two nuclei. Elsewhere it is only indi- 
cated by shading. It is completely absent in the centre of the ovum. Peculiar 
bodies of irregular shape, staining more deeply and continuous by means of 
processes with the reticulum, are present. They are probably merely expan- 
sions of the strands of the reticulum. The male pronucleus is on the opposite 
side of the ovum to the female, but rather nearer the centre. It does not, 
