DEVELOPMENT OF PEEIPATUS NOV^-ZEALANDIiE. 259 



Figs. 'ka—e. — Three transverse sections through an ovum containing three 

 nuclei, and in which the yolk has begun to segment. 



Fig. 4« shows the whole egg. At one pole a round nucleus is present, 



and the yolk has begun to segment, the yolk-spheres at that pole 



being smaller than over the rest of the egg. Oc. 2, obj. CC. 

 Fig. 4:b shows only the pole of the egg containing the second nucleus 



and the yolk segmentation. The nucleus is much lobed. Oc. 2, obj. D. 

 Fig. 4c passes through the third nucleus, and shows only a small portion 



of the egg. The nucleus is lobed and very irregular in shape, n. 



Nucleus. Fm. Protoplasm surrounding the nucleus. F. Yolk. F. S. 



Yolk segments. Oc. 2, obj. D. 



Fig. 5. — Transverse section through the protoplasmic pole of the ovum, 

 which is shown in surface view in Fig. 24. The protoplasm is seen to consist 

 of a reticulum, in which the nuclei lie irregularly, n. Nuclei. Pm. Proto- 

 plasm. F.S. Yolk segments. Oc. 2, obj. CC. 



Fig. 6. Section through a small portion of the protoplasmic pole of the 

 same egg as Fig. 5, highly magnified, to show the irregular arrangement of 

 the nuclei, twelve of them being closely packed together in a small reticulate 

 area of protoplasm. Oc. 4, obj. E. 



Fig. 7 a. — Transverse section through the protoplasmic pole of an ovum, 

 slightly older than that from which Figs. 5 and 6 were drawn, showing how 

 the protoplasm has spread over a larger portion of the surface of the egg ; it 

 still forms a perfectly continuous reticulum. Oc. 2, obj. D. 



Fig. 7 b. — Section through the same ovum near the limit of the protoplasmic 

 area, to show how the protoplasmic areas are connected together by strands. 

 Oc. 2, obj. D. 



Fig. 8. — Transverse section through the protoplasmic pole of an ovum, in 

 which the protoplasm extends over a larger area of the surface of the egg 

 than it did in the preceding figures. The protoplasmic segments are rather 

 more distinct from one another than they were in the preceding figures, but 

 are still connected by strands. Pm. S. Protoplasm segments. F. S. Yolk 

 segments. F. m. Vitelline membrane, n. Nuclei. Oc. 2, obj. D. 



Fig. 9. — Section through half of an egg of about the same stage as that shown 

 in Fig. 8, in which the protoplasmic segments are more distinct from one 

 another than is usually the case. n. Nuclei. Pm. S. Protoplasmic segments. 

 F. S. Yolk segments. V. m. Vitelline membrane. Oc. 2, obj. CC. 



Fig. 10. — Transverse section through an egg, in which the protoplasmic 

 segments have extended fully half-way round the periphery. The protoplasmic 

 areas are separated from one another by considerable tracts of yolk ; one area 

 lies quite at the surface, and contains a large round nucleus which appears 

 to be about to divide. Three protoplasmic masses are present in the central 

 yolk, one of which contains three chromatin particles. The yolk does not 



