Chapter III — 45 — Darlingtonia 



and there are no glands. If the absence of glands indicates anything 

 it is that in Darlingtonia the only digestion which may occur is that 

 induced by bacteria, and that this at least takes place has been testi- 

 fied by J. G. Lemmon in a letter to Canby who mentions the obser- 

 vation in a paper in 1875. Lemmon remarked that he detected a 

 strong smell of decay at some distance, as did Jones and others later. 



The structure of the nectar glands is quite unique, though they 

 evidently may be regarded as conforming to the Sanacenia type. 

 On the surface a gland appears as one of the epidermal cells, or if 

 compound from two to five or six such cells {6 — 18, 19, 22). It ap- 

 pears filled with cytoplasm and a nucleus is always distinctly visible, 

 sometimes two or three (in the thin superimposed cells). Focussing 

 more deeply the gland cells become larger and rounded in outhne. 

 The reason for this is understood when a section is examined {6 — 20, 

 21, 23). It is then seen that the diameter of the glands increases 

 with depth and is composed of a row of flat cells, evidently derived 

 by periclinal division of an original epidermal cell. Underlying each 

 gland (if simple) is usually a single parenchyma cell, which in the 

 glands of the outer surface is quite deep, suggesting to Macfarlane 

 the adjective "globoid" {6 — 20, 21). 



When the gland is compound there will be seen in section two 

 (rarely more because of the unfavorable chances of such a section) 

 tiers of flat cells. These glands are not only compound but are much 

 larger than those on the outer surface, where they are invariably small 

 (about the size of the stomata) and simple. Compound glands occur 

 in great numbers on the nectar roll, and, to a less extent, on the for- 

 ward interior face of the dome. 



When a pitcher is allowed to lie in a weak solution of methylene 

 blue, the glands of the outer surface become stained throughout, 

 though the surrounding epidermal cells remain colorless. There is 

 evidently ease of diffusion through the external cells. Macfarlane 

 explained this by the absence of cuticle from the outer gland cell, say- 

 ing that he could observe the torn edges of the cuticle in a surface 

 view, but I have been unable to verify this. By the evidence of ex- 

 posure to methylene blue it also appears that the wafls of the gland 

 are cutinized (Goebel) except at the base, as is the case with the 

 glands of other genera of the Sarraceniaceae. 



In the absence of digestive glands, but on the presumptive nutri- 

 tion of the plant from the decaying insects which are caught in great 

 numbers (Edwards counted 33 spp.), the question as to what part, if 

 any, of the interior surface of the tube can absorb the products of such 

 decay, is pertinent. We have seen that zone 4 in S. purpurea is devoid 

 of cuticle. In Darlingtonia it is surprising to note that the whole of 

 the surface from the lower limit of zone i, that is, below about two- 

 thirds of the dome, is capable of absorption. When a leaf is plunged 

 into a weak methylene blue solution for 20 hours the tissues, as far 

 as and including the outer part of the third layer of parenchyma, become 

 dyed, while no dye enters through the outer surface epidermis, except 

 through the nectar glands. There can hardly be any question, there- 

 fore, that the inner surface of the pitcher is capable of absorbing so- 

 lutes which result from the decay of insects within it. This is due, 



