288 LILIAN SHELDON. 



and seem to arise in the protoplasm itself. A transverse 

 section of an ovum at this stage is shown in fig. 27. As will 

 be there seen, the egg is now surrounded by a thin shell. 



The nucleus now loses its evenly spherical form and becomes 

 crinkled in outline. This appears to be due to the passage out 

 from it of portions of its substance which pass into the extra- 

 nuclear tissue in the form of round bodies of various sizes. 

 These bodies, like the portion of the nucleus from which they 

 are formed, are perfectly homogeneous, and stain with picro- 

 carmine a deep yellowish red. This process is shown in 

 fig. 28. The small yolk-globules are still present (coloured 

 yellow). The shell has increased in thickness. 



This process continues until all the wall of the nucleus is 

 dispersed, the central clear part appears to blend with the egg- 

 protoplasm, and the nucleolus remains behind lying in the 

 protoplasm. This condition is shown in fig. 29. The round 

 spheres derived from the nucleus remain unchanged. I believe 

 that these round spheres form part of the yolk of the 

 ovum, which question I shall further discuss later on in this 

 paper. 



All the above stages were very common and occurred to a 

 greater or less extent in all the ovaries which I cut of April, 

 July, and December, but the older stages, which I shall now 

 describe, were only found in the ovary in December, and not in 

 either April or July, a fact which supports the statement which 

 I made in a previous paper (16, p. 272) that the ova probably 

 pass into the oviduct in December. 



Fig. 31 represents a transverse section through an ovum in 

 which a small amount of yolk is present ; this is coloured yellow 

 in the diagram. A very obvious thing in this ovum is the 

 entire absence of any definite boundary line between the follicle 

 and the ovum itself, in fact, they pass into one another imper- 

 ceptibly. There is a small amount of yolk present in the form 

 of scattered spheres throughout the protoplasm of the ovum, 

 which latter has a reticular and vacuolate character. There 

 are also in the protoplasm small round or oval nuclei which in 

 every respect resemble those of the follicle> and it seems almost 



