Francis E. Lloyd — 100 — Carnivorous Plants 



In the seedling, the cotyledons withdraw from the seed during 

 germination and develop into broadly linear tapering members, sup- 

 plied with glands enabling them to capture prey (Franca). 



The leaf bears two kinds of glands, stalked mucilage glands and 

 sessile digestive glands {14 — i, 2, 6). Their position is determined if 

 at all only to a sHght extent by the three vascular bundles, from 

 which, however, they receive branchlets ending at the bases of the 

 glandular tissues. There are three double files of stalked glands, one 

 along each leaf margin, roughly speaking, and two rows along the 

 under leaf surface, one on each side of the midvein. The sessile glands 

 are more scattered, and apparently only in some degree determined in 

 position by the vascular tissues. Sessile glands occur on both upper 

 and under leaf surface, stalked glands only on the under surface and 

 along the margins. 



Structure of the glands. — Drosophyllum differs from Byblis in that 

 the glands, instead of being trichomes, are emergences, and, as Darwin 

 pointed out, have much the same structure as those of Drosera, with- 

 out, however, being endowed with the power of movement. This 

 refers of course to the stalked glands. These have a stout stalk sur- 

 mounted by a large nearly hemispherical capital, and, as Darw^in put 

 it, have the "appearance of miniature mushrooms." 



The capital {14 — 2) consists of three courses of cells running 

 parallel with the outer surface. The outer of these, the epidermis, is of 

 rather thick, wavy-walled cells, with strong buttress thickenings, stiffen- 

 ing the angles of the radial walls {14 — 3). The dense protoplasmic 

 contents and prominent nuclei speak for their glandular activity. 

 These are covered with a cuticle, which according to Fenner is finely 

 porous, thus permitting the exudation of the mucilaginous secretion. 

 I have not succeeded in convincing myself that the pores are optically 

 demonstrable, but it is certain that the cuticle offers no impediment to 

 the diffusion of methylene blue, for less than a minute's exposure to a 

 watery solution of this dye results in the deep staining of the whole 

 capital while the dye does not penetrate the remaining epidermis at 

 all. Meyer and Dewevre also failed to see the pores but demon- 

 strated on kiUing the escape through the cuticle of the pigment which 

 renders the gland conspicuous. They found also that lithium nitrate 

 taken up through the roots is found 12 hours later in the mucilaginous 

 secretion. The cells of the second course underlying the epidermis are 

 somewhat more irregular in form, but are likewise provided with but- 

 tress-thickenings in the radial walls, though they are not so numerous 

 and prominent as in the epidermal cells. The general character of 

 these two courses is the same; they were called, by Penzig (1877), the 

 secretion-layer. Underlying these two courses is a third, of flat cells, 

 of greater size in the transverse direction (with reference to the axis of 

 the gland) with their contiguous radial walls strongly cuticularized, so 

 that in a cleared preparation when suitably stained, as with congo red, 

 one sees a strong network lying within the capital. Contrary to an 

 earlier view (Solereder 1899, p. 367) not the entire but only the 

 radial walls are cuticularized, thus (Goebel 1891) leaving a free 

 diffusion passage. This feature is held in common with other gland- 

 ular structures described elsewhere. 



