(347) 
the ephemeral character of the suspensor in the other forms 
it is quite possible that such a structure may be formed here, 
but later lost. Cell-division at this stage proceeds at random 
and only at opposite ends is there any apparent regularity in 
the sequence of the cell-divisions. Cells at the proximal end 
appear at this stage to initiate the process by which the root- 
cap is differentiated, and at the distal end to form in that 
order which, in later embryos, shows them arranged in layers 
parallel with the epidermis. 
Trichosanthes 
Trichosanthes presents certain features which quite strongly 
suggest those found in Bryonops7s. In the origin of the 
ovule upon the placenta the conditions are quite similar, each 
flank of the placenta bearing a single series of ovules. The 
first indication of the formation of sporogenous tissue may be 
seen when the ovule is still merely a small elevation on the 
placenta. At this time the archesporium, consisting of a 
single cell, appears immediately below the epidermis at the 
apex of the young nucellus (fg. 52). It may readily be rec- 
ognized by the usual characters which mark sporogenous 
tissue. At this stage no differentiation of the ovule is appar- 
ent, but its rapid growth results in the distribution of its cells 
in confocal series as seen often in longitudinal section of the 
organ. 
The hypodermal archesporial cell divides to form the tape- 
tum and the spore-mother-cell. The former continues to 
divide by periclinal walls, thus forming an axial row of from 
ten to twelve cells. The sporogenous cell enlarges in the 
mean time, acquiring a nucleus which occupies most of the 
space within the walls of the cell (7g. 53). The process of 
spore-formation appears to be quite regular in 7rzchosanthes, 
that is the functional megaspore is one-fourth the spore- 
mother-cell. The first division results in the formation of two 
cells, of which the outer one, however, does not again divide. 
It immediately disorganizes, while the other cell, the lower of 
the two, proceeds to divide again transversely. The spindle 
