130T/VNY.] 
NATURAL HISTORY. 
553 
In such cases, however, its proper membrane is commonly 
obliterated, and its place supplied either by that of the 
nucleus, by the inner membrane of the ovulum, or, where 
both these are evanescent, by the testa itself. 
In other cases the albumen is formed by a deposition of 
granular matter in the cells of the nucleus. In some ot 
these cases the membrane of the amnios seems to be per- 
sistent, forming even in the ripe seed a proper coat for the 
embryo, the original attachment of whose radicle to the 
apex of this coat may also continue. This, at least, seems 
to me the most probable explanation of the structure of true 
Nymphaeacese, namely, Nuphar, Nymphaea, Euryale, Hy- 
dropeltis, and Cabomba, notwithstanding their very re- 
markable germination, as observed and figured in Nymphaea 
and Nuphar by Tittmann *. 
In support of this explanation, which differs from all 
those yet given, I may here advert to an observation pub- 
lished many years ago, though it seems to have escaped 
every author who has since written on the subject, name- 
ly, that before the maturity of the seed in Nymphaea- 
cem, the sacculus contains along with the embryo a (pulpy 
or semi-fluid) substance, which I then called Vitellus, ap- 
plying at that time this name to every body interposed 
between the albumen and embryo f. The opinion receives 
some confirmation also from the existence of an extremely 
fine filament, hitherto overlooked, which, originating from 
the centre of the lower surface of the sacculus, and passing 
through the hollow axis of the Albumen, probably connects 
this coat of the Embryo in an early stage with the base of 
the nucleus. 
* Keimung tier Pjlanzen, p. 19. et 27. tab. 3. et 4. 
t Prodr, Flor. Nov, HoU. i, p. 306. 
