1885.] STRUCTURE OF THE OVUM IN THE DIP.VOI. 513 



These, like the last, are connected with the germinal epithelium, 

 coreriii» the outside of the ovary, by a pedicle of epithelial cells, 

 which is nearly of t'ue same width as the whole structure and its 

 follicle. The germinal epithelium is in a condition of very active 

 multiplication, the nuclei being very closely crowded together. 



The layers of cells which surround the central mass cannot be 

 differentiated ; they present the appeara'ice of a mass of cells con- 

 tinuous with the germinal epithelium and forming a laver of cells 

 three or four deep ; only here and there (fig. 10, bl) were traces of the 

 irruption of the stroma in the shape of small blood-capillaries. The 

 cells which constitute this peripheral layer are preciselv similar in 

 their character to the cells which form the outermost of the peripheral 

 layers in Stage I. 



In two instances belonging to this stage, which I have been able to 

 study, the homogeneous darkly-staining mass produced by the 

 solution and fusion (?) of the protoplasm of the central cells was 

 much more in amount than in the last described stage. Fig. 1 1 

 of Plate LIII. represents the central mass of cells, which are seen to 

 be divided up into partly or entirely isolated clumps by the formation 

 of this homogeneous mass, which contains also free nuclei (fig. 1 1, n). 

 In the third case the condition of the central cells, so far as this 

 fused mass of protoplasmic material is concerned, was much the same 

 as in Stage I. 



On the whole these facts appear to indicate that the bodies belong 

 to a somewhat earlier stage than those just described and shown in 

 fig. 1 of Plate LII. Their small size, the undifferentiated condition 

 of the peripheral layers, as well as the very small amount of stroma 

 (blood-vessels) between the cells of these layers, appear to me to 

 point to this conclusion. On the other hand, the greater amount of 

 change in the central cells, i. e. the increased amount of the deeplj'- 

 staining fluid substance between isolated clumps of cells, is against 

 such a supposition, as it is evidently a further development of a 

 process which lias only just commenced in the developing structure 

 which I have last described. This latter reason is perhaps not a very 

 powerful argument, because it may easily be supposed that the pro- 

 duction of the semifluid protoplasmic substance may be hastened or 

 retarded ; the same may be said with regard to the specialization of 

 the follicular layers, only that a specialization in the instances observed 

 by myself goes together with increase of size of the whole body. 

 Accordingly I am inclined to believe that the bodies displayed in 

 fig. 9 of Plate LIII. belong to a younger stage than those illustrated 

 in fig. 1 of Plate LII. 



Stage II. — The different layers composing the follicle are more 

 differentiated, and each individual layer is now quite recognizable. 



Commencing from theoutside, we have the secondary follicular layer, 

 between which and the follicular layer proper is a well differentiated 

 vascular layer, which is easily to be made out through the whole 

 circumference ; the blood-vessels are filled with blood, and appear 

 as round, elliptical, or elongated according to the angle of the 

 section. The follicular layer has the appearance of being only 



pRoc. ZooL. Soc— 1886, No, XXXIV. 34 



