OF THE RAPHE IN SEEDS. 99 
the testa, and which by pressure leaves a corresponding groove on the surface of the 
albumen, is singular in its form, on account of its retroversion in the manner I have 
detailed, both here and in my Monograph of the genus. Its nature does not appear to 
have occurred to Mr. Thwaites, for he describes it merely as * a whitish raised line, which 
is very conspicuous on the outside of the seed, passing quite round it lengthwise, and 
consisting of à fillet of spiral vessels lying between the two thin coats or layers of the 
testa.” The nature of this fillet is soon ascertained by tracing it to its origin, and I have 
again referred to the parts of my two analyses which I have preserved, and these confirm 
my previous inference. As its form and position involve other considerations of some im- 
portance, it is desirable to describe it more in detail. On examining the putamen, which 
is the lignified endocarp of the fruit, we find it of an oval form, slightly flattened on one 
side, along which is observed a longitudinal groove, in which is imbedded a thick cord or 
bundle of fibres, which is easily raised from the channel, and is found to penetrate an 
aperture in the upper extremity of the groove: some fibres proceeding from the stigma 
here join it, and the cord now reduced to a thread, after its passage through that aper- 
ture into the cell, becomes attached to the testa of the seed, on a small protuberance 
near its apex; it then assumes the features of a prominent line upon it, and descends 
along one angle of the dorsal face of the seed, to near its base, then curves round this, 
and ascends along the other angle of the same face, to a hollow in the summit, beneath 
the apical protuberance just mentioned, where it disappears, describing in its course a 
horse-shoe, ‘or rather an oval curve: and this is the “ whitish raised line” described by 
Mr. Thwaites. The nourishing vessels are thus distinctly apparent throughout their 
entire course, from the external base of the putamen to the vanishing point of the thread 
just described, in one continuous line: the external portion of this cord is evidently the 
placentary axis of the dissepiment of the normal bilocular ovarium, for in the 2-celled 
and 2-seeded fruit which I have mentioned, where the seeds were separated by a distinct 
partition, this same cord was seen imbedded in the line of its axis, and became furcated 
on arriving at the summit, each branch passing through a double aperture into the two 
cells, where it attached itself to the apex of each seed, and continued in its course as the 
“whitish raised line” of Mr. Thwaites: this thread therefore bears the character of a 
raphe ; but as its form is very peculiar, it is well to compare it with the same organ in 
other genera of this family. € : à 
The development of the seed in Stemonurus is precisely similar to that in Pounontia, as 
I have elsewhere shown, agreeing even in the same relative size, shape, and position of 
the embryo, differing only in the singular extension of the raphe, and the presence of * 
large vacuity in the centre of the albumen, lined with thin pellicular plates. In P asset 
as in other genera of the Zcacinaceæ, the raphe originates as in Stemonurus ; am 
course is along the middle of the dorsal face, and it loses itself at the opposite = = 
ledonary extremity of the testa, according to the law of anatropal ia a vas 
latter genus, contrary to general rule, the descent of the raphe is along one P" sita x 
seed, and, after crossing the lower part, it ascends up the other Ke VO Meee eis poni 
from which it started, and is lost in the integument, close to the extremity of the radicle : 
which is always inclined a little towards the dorsal face, leaves 
the raphe in this course, 02 
