Francis E. Lloyd — 14 — Carnivorous Plants 



details of structure. They are unicellular hairs with the bases embed- 

 ded in a raised mass of epidermis and underlying parenchyma. They 

 taper from the base gradually to the sharp tip, and the cuticle is 

 raised to form folds or ridges, beginning at or near the base and con- 

 verging on the apex, where they gradually fade away. These ridges 

 are more pronounced on the hairs of the conductive surface, and are 

 much weaker to scarcely distinct on the hairs of the detentive surface. 

 The former are relatively longer, more slender and distinctly flexible, 

 the more so in the lower parts of the conductive surface. Krafft 

 suggested that these ridges have use as strengthening elements, but 

 the effect is not to make the hairs rigid. They may make it more 

 difficult for flies to use their foot organs. Their chief eflficiency lies, 

 I imagine, in their number and flexibility, so that an insect cannot 

 place its feet on the bell surface, but can only hook onto the hairs 

 which by their flexibility give way and permit the insect to slip into 

 the pitcher. The hairs of the detentive surface on the other hand 

 are short, very thick walled and rigid, thereby making escape difficult. 

 Bentham (1840) said of these that ''they have all the appearance of 

 ordinary secreting hairs," but this was a mistake. They are cer- 

 tainly not secretory. 



The structure of the nectar gland of the pitcher in Heliampkora 

 has been described, though not quite correctly, by Krafft (1896). 

 There are, for purposes of description, two kinds: (a) those which 

 are relatively small and have few cells, about 12 in number (2 — 10). 

 These are found scattered over the whole of the bell, and on the outer 

 surfaces, including the wings, and are regarded as nectar glands 

 by GoEBEL, who detected a sweetness in the excreted fluid; and 

 (b) large glands found only on the inner surface of the spoon (2 — 7). 

 Krafft spoke of three kinds of glands, distinguishing those on the 

 inner from those on the outer surfaces. But they are all quite the 

 same in structure, differing somewhat in size, those on the outer sur- 

 faces being shallower, the glandular cells of a gland having little more 

 depth than that of the surrounding epidermis. 



The structure of the smaller glands is as follows: They appear in 

 surface view to consist of six cells, four in a single course in the level 

 of the epidermis, covered partially by two cells, the "cover cells" of 

 GoEBEL. The area of the exposed surface of the gland is about equal 

 to that of a stoma. It is difficult to resist the theory that the glands 

 are derived phylogenetically from stomata, but there is no support 

 for this beyond the suggestive appearance of the two cover cells. 

 Beneath the course of four cells, there is a second inner course of cells 

 which appeared to Krafft to be four in number. One usually can 

 count at least six cells, two cells lying beneath the two cover cells. 

 But the glands are of irregular structure, and one cannot say definitely 

 that there are only so many cells. These constitute the gland proper, 

 and are all derived from the epidermis. They are surrounded by a 

 cuticularized membrane, except at the base, which, though being 

 partially covered with this membrane, is not entirely so, there being 

 left a "window" (Krafft used this word), so that the active gland 

 cells lie in direct contact with usually two, sometimes one, or three 

 to four, parenchyma cells below. 



