OVUM IN THE OAPB AND NEW ZEALAND PEEIPATUS. 289 



certain that these must have migrated from the latter, a process 

 which would be simple in the absence of any separation between 

 the ovum and the follicle. A few yolk-spheres were present in 

 the tissue of the follicle itself. There was no trace of any 

 germinal vesicle or germinal spot. The shell was thin. This 

 ovum measured 3 mm. iu its greatest diameter ; as I neglected 

 to measure these eggs before cutting, I am not able to state 

 their length. 



At the next stage on which I have observations, and which 

 was found in an ovum from the same ovary as the last, there 

 is a considerable increase in size, the ovum measuring "5 mm. 

 in diameter. This increase seems to be due principally to a 

 much greater abundance of yolk-spheres in it, the protoplasm 

 being distributed among them as a very loose or sparse reti- 

 culum. The most remarkable fact about the ova of this stage 

 is that the stalks by which they are connected with the ovary 

 are hollow. One of these eggs is shown, in section, in fig. 32. 

 As is there shown, the wall of the follicular stalk thins out 

 where it reaches the ovum, and passes imperceptibly into its 

 wall. In the hollow of the stalk there are a large number of 

 yolk-spheres and a few nuclei, resembling those of the walls 

 of the stalk, which appear to be passing down it into the ovum 

 from the ovary, which contains in its cavity a large amount of 

 yolk, as is shown in fig. 26, which represents a transverse 

 section through this ovary. There are a few nuclei of the walls 

 of the stalk, which appear to be about to be detached and 

 pass into its cavity. There are none of these small nuclei iu 

 the deeper part of the ovum, from which I infer that they, 

 together with those which had migrated from the follicle in the 

 previous stage, became converted into yolk. 



In the next stage, a transverse section through an ovum of 

 which is represented in fig. 30, there has been a slight increase 

 in size, the diameter being -56 mm. This ovum is completely 

 filled with yolk, and no protoplasm is present, except in the 

 form of a large, nearly round nucleus, which lies just beneath 

 the point of attachment. This nucleus stains deeply and uni- 

 formly, with the exception of a few more deeply staining 



