DEVELOPMENT OF PEKIPATUS NOViE-ZEALANDI^. 235 



embedded in a large mass of protoplasm, and is very much 

 lobed in form. In fig. 4 c, which passes through the third 

 nucleus, two of the yolk-segments possess a small amount of 

 protoplasm, and there is a very large amount in the segment 

 which contains the nucleus. The nucleus itself is very peculiar 

 in shape, and is made up of a large number of lobes. 



At the next stage the yolk is segmented throughout the 

 whole egg, but the nuclei are still confined to the protoplasmic 

 area. In the fresh state the yolk-segments are very clearly 

 seen over the whole surface, so that in a view of the whole egg 

 it appears to be made up of a number of round segments, all 

 resembling one another in size and shape ; a surface view of 

 such an egg is figured in fig. 23. It is this appearance which 

 probably led Hutton and Kennel to state that the segmenta- 

 tion was holoblastic, but the fact that it is only due to the 

 yolk segmentation is quite clear when sections of the egg are 

 examined. 



The yolk-segments are much smaller at the protoplasmic 

 area, and the yolk-spheres composing them are also smaller 

 than they are over the rest of the egg. 



The protoplasm is still mainly confined to the protoplasmic 

 area, but small quantities are present in other regions ; it con- 

 sists of a reticulum very indefinitely segmented, the whole 

 being intimately connected by strands passing over from one 

 aggregation of protoplasm to another. Nuclei are scattered 

 about very irregularly through the protoplasm, in some places 

 two or three lying close together, while in others there is 

 a considerable tract of protoplasm devoid of any nucleus. 

 Sections through the protoplasmic area of such an egg are 

 shown in figs. 7 a and 7 h. 



A surface view of an egg slightly older than the preceding 

 is shown in fig. 24 ; the yolk segmentation on the surface of 

 the egg has been obliterated in the course of preservation, but 

 at the protoplasmic area the segments are clearly seen, the 

 presence of the protoplasm having rendered the surface at this 

 point less easily disintegrated. This egg bears a very close 

 resemblance to those figured by Mr. Sedgwick in the first part 



