Chapter VI — 93 — Genlisea 



to allow only very small animals to enter and then to hold them ir- 

 revocably". This remarkable structure is as follows. 



In form, the bulb and tubular neck (the tube) may be compared to 

 a chianti flask. Within the flask there are two ridges (if we were 

 speaking of an ovary they would be called placentae), one ventral and 

 one dorsal, extending from the base up the sides about two-thirds the 

 distance to the neck above {12 — 10). Within the tissue of the ridges 

 runs in each a branch of the single vascular strand arriving from the 

 footstalk, while the surface bears numerous glands, which may be pre- 

 sumed to be digestive and absorptive, either but probably both. A 

 few additional glands are to be found on the rest of the surface. The 

 two vascular strands, each of a single spiral vessel accompanied by a 

 thin strand of phloem, the one dorsal and the other ventral, pass up- 

 ward from the bulb into the walls of the tube without change of di- 

 rection. Near the mouth of the tube they divide, a branch from each 

 supplying each arm, which then has two vascular strands quite as if it 

 were a closed tube branched from the main tube. The inner surface 

 of the tube is broken up into a series of some forty transverse ridges 

 each formed of a transverse row of radially thickened cells, each of 

 which sends downward toward the flask a stiff curved trichome {g — 

 8; 12 — 8, 9, 13). Of these cells there are about 50, so that there are 

 that number of slender stiff bristles projecting inward and downward 

 from each ridge. Each section of the tube below and including a 

 transverse ridge is therefore of the form of the entrance to an eel trap, 

 or lobster pot, if you will. The whole tube, 0.13 to 0.42 mm. inside 

 diameter, is a series of such traps, some forty to fifty in number, each 

 with its funnel extending into the next below. In addition to these 

 downwardly directed hairs, and just below the ridges in each section 

 there are one or two transverse rows of glandular trichomes {12 — 8, 

 9, 16). The zone where these occur broadens toward the outer end 

 of the tube and is composed of wavy-walled cells, while the bristle 

 bearing cells are conspicuously straight and narrow, lengthwise the 

 tube. 



On approaching the open end, the tube widens somewhat, and 

 spreads out to form the arms. The open end is formed of the upper 

 and lower sides to form two lips, the upper (ventral) somewhat shorter 

 than the lower, and fixed in a position a little distance apart by the 

 ballooned cells above mentioned (prop-cells) (77 — 1-4; 12 — 2, 3). 

 These are closely enough placed so that in between, alternating with 

 them, a series of funnels, guarded by inward pointing hairs, is formed. 

 This is repeated along the open slit of the arm (77 — ^11) quite to the 

 apex. 



In passing up into the arms, the same general structure described 

 for the tube is repeated {12 — i, 4), but the ridges are now curved 

 obhquely, comformably with the directions and amounts of growth 

 (77 — 6, 9). Along the edges of the arm, as one inspects it if laid 

 open, the ridges run almost parallel thereto, each ridge beginning in a 

 prop-cell. Passing obliquely inward and forward they gradually ap- 

 proach the other edge in a harmonic curve. When past the middle of 

 the arm they bend rather sharply back and approach a direction again 

 parallel to the other edge and then end at the scar-like depression 



