OF THE RAPHE IN SEEDS. 103 
found the end of the radicle extending a little beyond the mouth of the cavity : this con- 
jecture is confirmed by the drawings of Gærtner (De Fruct. tab. 208). A similar per- 
sistence of the embryo-sac, and its forming the lining of a large cavity in the albumen, 
which is thus nearly separated into two parallel plates, and the occasional protrusion of 
this sac beyond the limit of the albumen, occur also in Strychnos and Ignatia, as may be 
seen from the figures given by Gærtner (De Fruct. tab. 189). The protrusion of a portion 
of the embryo-sac, and with it of the radicle, in the manner above conjectured to exist in 
Diospyros, is known to occur in Myzodendron, where it is well figured by Dr. Hooker in 
his * Flora Antarctica,’ plate 104. fig. 18 & 19; and in plate 105. fig. 17, 18 & 19*. A 
singular example of the persistence of the embryo-sac is afforded in Marantacee : this 
occurs in the genus Thalia, where two large vacuities are seen in its copious albumen, on 
each side of the embryo: these are the persistent sacs in which two abortive embryos had 
existed: this curious fact was first recorded by Mr. Brown nearly fifty years ago (Prodr. 
p- 807): it is one of the few instances that occur, where several embryo-sacs are generated 
in the same ovule. 
In regard to the origin of the albumen in seeds, it was shown by Gærtner (loc. cit. 
Introd. 188), and Mr. Brown confirms it as a well-established fact (Linn. Trans. x. 36), 
that it is merely that condensed portion of the amniotic fluid which remains unabsorbed 
by the embryo at the termination of its growth. This excessive portion of the fluid is 
generally expelled from the embryo-sac (quintine, Mirbel), and is deposited and consoli- 
dated in the cellular tissue of the quartine, which lines the tercine (nucleus, Brown) when 
- it constitutes the albumen, and in ordinary cases the sac becomes absorbed without 
leaving any trace of its existence. Besides the instances of its permanence just given, its 
existence under other peculiar circumstances was first shown by Mr. Brown, in the 
Nympheacee, where a portion of the redundant amniotic fluid forms a separate and 
second albuminous deposit, immediately surrounding the embryo, which he has aptly 
named the vitellus, and which in the ripe seed is found lodged in an exserted portion of 
the embryo-sac : it is therefore always seen at one extremity, outside of the great mass of 
the ordinary albumen: when this occurs, it is accompanied by the appearance of sr 
tubular vacant space in the axis of the albumen which is the opposite “ere > 
persistent embryo-sac, of which the other portion containing the VAN À eonun 
tion. This has been shown to exist among Dicotyledones, in the Nymphæaceæ, Le: 
bacee, Saururacee, Piperaceæ, &e., and in several cases among Monocoty — ( pe sj 
dix, King’s Voy. p. 21). A very excellent illustration of this 7 e n 
the admirable work of Dr. Asa Gray (Gen. Pl. Un. St.), where evidence of its preser 
3 ia, in pl. 38, 39, 43 & 44. 
shown in the seeds of Nymphæa, Nuphar, Cabomba, and Brasenta, MP? be formed 
Mr. Brown observes (loc. cit. p. 22), * that the albumen, Pops ly so called, ng (embryo- 
by a deposition or secretion of granular matter in the ufin af the vues pri 
Sac) “or in those of the nucleus itself” (tercine or quartine); or lastly, 
3 in Ceratophyllum the principal 
* Schleiden (Linnæa, xi. 526. tab. 11. figs. 12, 13) has shown the curious fact, that in Ceratop 
eee : le. 
i hi ine seed remains investing the plumule, 
Portion of the embryo is developed outside of the embryo-sac, which in the T. the embryo-sac around the plumule, 
and enclosed within the cotyledons; a small quantity of albumen is deposited in imple thin integumentary covering. 
but none is formed outside of the large cotyledons, which are invested only 2e 
