OVUM IN THE CAPE AND NEW ZEALAND PERIPATUS. 303 



first polar body. The histological characters of the polar body (Fig. 

 20 b) are precisely similar to those of the nucleus and its surrounding 

 protoplasm. 



Fig. 21. — Male pronucleus of P. Balfouri shortly after its formation. 

 Pron. (J. Male pronucleus. Zeiss, oc. 3, Reichert's J^th oil imm. 



Fig. 22. — Transverse section through one half of the ovary of P. Balfouri 

 in December. C. 0. Cavity of ovarian tube. Fol. Follicle. G. S. Germinal 

 spot. G. V. Germinal vesicle. Ov. Ovum. Zeiss, oc. 3, obj. C G. 



Fig. 23. — Ovum of P. Balfouri of April, while the nucleus is still in the 

 centre. Letters as in Fig. 22. Magnified 600 diameters. 



Fig. 24. — Ovarian ovum of P. Balfouri after the disappearance of the 

 nucleus. Magnified 600 diameters. 



Fig. 25. — Ovum of P. Balfouri, in which the male and female pronuclei 

 lie close together and are apparently about to conjugate. Magnified 600 

 diameters. 



N.B. — The remaining figures are of P. novse-zealandise; in them the 

 yolk is coloured yellow. 



Fig. 26. — Transverse section of the ovary of P. novee-zealandise. C. 0. 

 Cavity of ovarian tube. Ov. Ovum. Per. Wall of pericardium. Zeiss, oc. 

 3, obj. A. 



Fig, 27. — Ovum of P. novse-zealandise, in which the germinal vesicle 

 is central and has a homogeneous regular wall. Fol. Follicle. G.S. Germinal 

 spot. G. V. Germinal vesicle. 0. S. Eggshell. 



Fig. 28. — Ovum of P. novse-zealandiae, in which the germinal vesicle 

 has a crinkled outline. Letters as in last figure. 



Fig. 29. — Ovum in which the germinal vesicle has broken down. 



Fig. 30. — Ovum with large excentric nucleus and great mass of yolk, from 

 a December ovary. 



Fig. 31. — Ovum in which the germinal vesicle is absent, showing the passage 

 into the ovum of nuclei of the follicle. Fol. Follicle. Fol. Nu, Nuclei from 

 the follicle in substance of ovum, Ov. Ovum, 



Fig. 32. — Ovum in which the peduncle has become hollow, and yolk appears 

 to be passing down it from the cavity of the ovarian tubes. 



