and Affinities of Trapella. 109 
Comparing the ovary in the young bud (Fig. 17) and in the 
mature flower (Fig. 15), it is unquestionable that that part 
which is inferior (i. e. below the insertion of the calyx) 
constitutes a much larger proportion of the whole ovary in 
the flower than in the bud ; and this difference is more 
marked in the fruit. The elongation of the fertilized ovule 
would appear to be extremely rapid (see p. 89), and due, to a 
great extent, to the active growth of the lower apical tissue of 
the ovule. 
It being, for some reason, advantageous for this stage (i. e. 
the elongation of the ovule and development of the endosperm) 
to be rapidly passed through, it is not surprising to find 
developed a special organ, by means of which ultimately the 
embryo is enabled to make use of the food contained in the 
lower ovular tissue. Hence we find (1) the absorptive organ, 
in this case formed from the modified apical cap-cell, at an 
early period filled with transitory starch-grains ; (2) the endo- 
sperm growing at the expense of the surrounding tissue, 
from which nourishment is absorbed, partly direct and partly 
by the special absorptive organ in question ; (3) the embryo 
growing at the expense of the endosperm. 
Finally, the fact of the prominent spines being in Trapella 
borne by the invaginated part of the fruit, whilst in Pedalium 
they arise from a superior fruit, is obviously correlated with 
the grand modifications undergone in the floral relations. 
The possession still in the ripe seed of a thin layer of endo- 
sperm points towards, rather than away from, the Pedalinaceous 
affinity. The Order is usually given as ‘ exalbuminous, 5 and 
Trapella itself even was at first described as such ; for, from the 
reduction of the integument to a single layer of flattened cells, 
it was impossible then without embryological evidence to say 
that the described testa was not such in reality. But not 
only is the seed of Trapella provided with several layers of 
endosperm, but in Pedalium 1 also a like state of things exists. 
Indeed were investigation pushed further in the same direction, 
1 Baillon in the new part of his Histoire des Plantes (vol. ix. p. 444) describes the 
endosperm in this genus — ‘ albumine membraniformi .’ 
