OF THE VERTEBRATE OVARY. 563 



In the first place many of the modified nuclei acquire fresh 

 characters, and it becomes necessary to divide the modified 

 nuclei into two categories. In both of these the outer boundary 

 of the nucleus is formed by a very delicate membrane, the space 

 within which is perfectly clear except for the granular body. 

 In the variety which now appears in considerable numbers the 

 granular body has an irregular star-like form. The rays of the 

 star are formed of fibres frequently knobbed at their extremi- 

 ties, and the centre of the star usually occupies an eccentric 

 position. Typical examples of this form of modified nucleus, 

 which may be spoken of as the stellate variety, are represented 

 on PI. 25, fig. 17 ; between it and the older granular variety 

 there is an infinite series of gradations, many of which are repre- 

 sented on PI. 24, figs. 12, 14, 15, 16. Certain of the stellate 

 nuclei exhibit two centres instead of one, and in some cases, 

 like that represented on PI. 25, fig. 19, the stellate body of two 

 nuclei is found united. Both of these forms are possibly modi- 

 fications of the spindle-like form assumed by nuclei in the act 

 of dividing, and may be used in proving that the nests increase 

 in size by the division of the contained nuclei. In addition to 

 the normal primitive ova, a few of which are still present, there 

 are to be found, chiefly in the deeper layers of the germinal 

 epithelium, larger ova differing considerably from the primitive 

 ova. They form the permanent ova (PI. 24, fig. 3 o). Their 

 average diameter is 0^04 mm., compared with 003 mm., the 

 diameter of original primitive ova. The protoplasm of which 

 they are composed is granular, but at first a membrane can 

 hardly be distinguished around them ; their nucleus is rela- 

 tively large, O'O2 O'O2/ mm. in diameter. It presents the 

 characters ascribed by Eimer 1 , and many other recent authors', 

 to typical nuclei (vide PI. 24, fig. 3, and PI. 24, 25, figs. 13, 14, 15, 

 1 6, 17, 1 8). It is bounded by a distinct membrane, within which 

 is a more or less central nucleolus from which a number of radial 

 fibres which stain very deeply pass to the surface ; here they 

 form immediately internal to the membrane a network with 

 granules at the nodal points. In some instances the regularity 

 of the arrangement of these fibres is very great, in other in- 



1 Archiv f. micr. An at. Vol. xiv. 



- Vide especially Klein, Quart. Jonrn. of Mic. Set. July 1878. 



