226 PROFESSOR ALEXANDER DICKSON ON THE EMBRYOGENY OF 
but more usually it extends itself obliquely outwards and downwards; sometimes 
very markedly so, as is seen in the more advanced stage represented in Plate 
XVI. fig. 22, where it extends quite out to the vascular bundle of the median 
rib or ridge of the fruit-lobe. Ihave not been able to trace how far the two 
root-processes in 7. peregrinum ultimately extend themselves, but probably 
they proceed the whole length of the carpel and placenta respectively, as in 7. 
majus. In fig, 22 the extra-seminal process is seen to extend for a considerable 
distance in the substance of the carpel; but its whole length is not seen in the 
section, the end having evidently been cut away in making the preparation. 
T. speciosum, Endl. and Poeppig. 
In this species (belonging to the Chymocarpus section of the genus, the fruit- 
lobes in which are destitute of ridges, and when ripe are somewhat drupaceous 
in character) the ovule departs widely from the marked anatropal form it pre- 
sents in 7. majus and T. peregrinum. The hilum (Plate XIV. fig. 1 2) is of 
great extent, reaching from the neighbourhood of the micropyle (mic) to that of 
the chalaza (ch). At the period of flowering the nucleus (z) is slightly curved, 
while its base or chalazal region is just sufficiently removed from the hilum to 
leave a small space traversed by vessels, which may be described as a very short 
raphe.* This peculiar form of ovule may be regarded as an intermediate one 
between the half-anatropal and the campylotropal. A somewhat analogous 
condition is that observed in such Leguminosz as the common Bean or Pea, 
where, however, the chalaza is at some little distance from the hilum, and where, 
consequently, the raphe is more distinctly marked. The nucleus is broadest at 
its base, becoming rather rapidly narrowed towards its pointed apex. The 
embryo-sac (se) is elongated, nearly cylindrical, and pointed at its micro- 
pylar extremity or apex. At the time of flowering the embryo-sac appears to 
have produced complete absorption of the narrowed portion of the nucleus 
towards the micropyle, and thus comes to be in immediate contact with the 
integuments. The integuments are two in number, and the micropyle is formed 
by the endostome as in 7. majus. The germinal vesicle (gv) (I can only speak 
to one with certainty, though probably there is a greater number) is a delicate 
ovoid nucleated cell with finely granular protoplasm, and occupies the apex of 
the embryo-sac. It is represented in the figure as entangled in a crumpled-up 
portion of the embryo-sac, and thus somewhat out of position. In this figure, 
and in some of the succeeding ones, the hemispherical, or slightly conical, 
extremity of the axile placenta (pv) is distinctly shown, representing the apex, 
* ScuierpEn (“ Nova Acta Acad. C. L. C. Nat. Cur.,” tom xix. tab, viii. fig. 126) gives a figure of 
the ovule of 7. (Chymocarpus) pentaphyllum, where it would appear that the anatropal character is much 
more distinctly present, the raphe being of considerable lencth. 

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