Mr. J. Miers on the Winteracese. 33 



is the nucleolus or "germinal spot." There is seldom more 

 than one ovum at a time in an appreciably advanced stage of 

 development (fig. 10 d), and, if there be two, one is much more 

 so than the other (fig. 11 d, e). 



As the ovum, in process of development, increases in size 

 (fig. \0d), yelk-granules are developed in its endoplasm, — in 

 fact, the endoplasm becomes the yelk; the germinal vesicle 

 enlarges ; it also presents an endoplasm in its interior, that is, 

 in the " transparent area," in which several distinct granules or 

 points appear (fig. 11 /), that become respectively the nuclei of 

 so many new cells (fig. 12 /), and when the latter are nearly 

 formed, the germinal spot or nucleolus perishes (g). The ovum 

 now appears to have attained its largest dimensions (fig. 1 1 d) ; 

 but the next stage, viz. the disappearance of the germinal vesicle 

 and the liberation of its contents, I have not witnessed. It is 

 from the germinal vesicle undergoing these changes that I have 

 assumed the single ovicell to undergo similar ones, prior to the 

 development of the "group" of ova; that is, that those of the 

 germinal vesicle are but a repetition of what have occurred in 

 the first ovicell. How far I am right in this matter, is left for 

 others to decide. 1 would here also remark, that the granules 

 or cells of the yelk appear to be multiplied by that process of 

 cell-formation called "budding" (fig. 51), so beautifully seen 

 in the little Lemna-Mke Physodictyon (Kz.), and the so-called 

 " ferment-cells," and that it bears a close resemblance to that 

 which I have described in the "ovules" of Spongilla* and 

 Euglenaf. 



[To be continued.] 



X.— On the Winteracese. By John Miers, F.R.S., F.L.S. &c. 



The only two genera belonging to this small group that were 

 known in the time of Jussieu, were placed by that celebrated 



* Annals, vol. xviii. p. 231. pi. 6. fig. 39. 



f Idem, vol. xx. pi. 1. fig. 16. Since my description of the " Ultimate 

 Structure of Spongilla" was published in this volume, I can of course no 

 longer regard the germs in the spherical cells of the " capsule" as " ovules," 

 but as the contents of these cells, which themselves are the ova, — each 

 spherical cell in totality producing an " ampullaceous sac," which appears 

 to me to correspond to the polype of a polypidom. This would make the 

 " germs" analogous to the " yelk-granules" of the ovum of Nais, and hence 

 also the analogous budding appearance. I have also described a similar 

 budding in the cells of Euglena viridis (l. c), and there is something like 

 this again in the production of the oleaginous and amyliferous cells (?) of 

 the Diatomese ; while latterly it has struck me that these may be produced 

 by a budding in the first instance from what I have termed the " glair- 

 eell" (Annals, xviii. p. 241). 



Ann. & Mag. N. Hist. Ser. 3. Vol. ii. 3 



