K.—BOTANY 215 
material, found growing in the vicinity of Montreal. It is well adapted 
to motion picture photography, and I show you some results. 
Irrespective of species, the plant body consists of a main axis with 
verticillate lateral axes, each member of which normally bears a terminal 
trap. In some species the trap is wholly devoid of appendages ; in others 
a proboscis-like upturning extension of the lower lip of the entrance is 
to be found, e.g. U. elephas Luetz. The walls are thin and bear three 
kinds of trichomes on the outer surface (Lloyd, 1933), one of which secretes 
a fatty oil. The interior surface bears numerous quadrifids and a dense 
row of bifids on the inner flank of the threshold bolster. 
From our present point of view the point of interest is the form and 
functioning of the door and threshold. These are, in structural detail, 
very different from the foregoing. The most readily observable differ- 
ence is the presence of a radiating group of tripping trichomes, arising 
from a knob-like protuberance placed a trifle above the middle point of 
the door at the upper limit of the middle piece, which is here very large 
but fundamentally like that of vulgaris. The trichomes are of two kinds 
in U. purpurea, of only one kind in U. elephas, U. cucullata, etc. Each 
trichome consists of a long, tapering, terminally expanded cell bearing 
a short, disc-shaped mid-cell, this bearing a spherical capitai cell with 
a much enlarged cuticle ; or, in other species, the end cell may be fusiform 
(Goebel, 1891). At the periphery of the tubercle the end cell is much 
smaller, as is the expanded outer end of the stalk cell. This difference 
has probably no significance. ‘These are the only trichomes on the door 
in U. purpurea ; in cucullata there is in addition a patch of short, clavate 
trichomes forming an oval group below the tubercle. 
The door consists of two chief regions, the middle piece below the 
tubercle and the sigmoid (the outer) hinge. The relative thickness of the 
two courses of cells changes as we proceed from the outer edge to the 
tubercle, so that the maximum flexure can occur where the outer cells 
are the thinnest, namely, just above the cuticle. It is here that the door 
chiefly bends on being opened. The lateral region is similar in structure 
to the outer hinge. The middle piece is massive, the cells being of equal 
thickness. The edge of the door is beaded with a three-quarters bead of 
some thickness, the bead being turned outward. When the trap is set this 
bead rests along the middle zone of the threshold, the velum resting against 
the door edge, over the beading. 
The threshold is narrow in the middle, widening fanwise toward the 
sides, where the door is attached to it. In its narrower middle part the 
outer zone bears an ample velum, consisting chiefly of the ballooned 
cuticles of the component cells, the middle zone cells contributing little, 
contrary to the case of vulgaris. ‘The middle zone is narrow, of small and 
compact cells, and is slightly dished to receive the door edge. The outer 
zone is unique in having the cuticles enlarged and filled with a stiff 
mucilage (a hydrolysed cellulose probably), forming a resisting ridge 
against which the door rests when the trap is set. The emplacement of 
the door otherwise is as in vulgaris, the lateral reaches lying against the 
broader lateral reaches of the threshold, where a broader zone of velum 
cells occurs. 
