HISTOLOGY OF riTCHEll PLANTS. 157 



appeared to possess a double cell-wall, the outermost one being 

 more refractive than the inner, in fact presenting the same appear- 

 ance as the so-called canals, the inner being evidently different in 

 texture, and wholly enclosed. This inner layer Dr. Tait refers to the 

 epidermal cell, and the outer one to the protoplasm of the so-called 

 intercellular canals, for their origin. Fig. 5 is a section of one of 

 these hairs, and it is seen that there is no communication between 

 it and the adjoining cells. In Fig. 2 their structure is distinctly 

 shown. The section from which this figure was drawn, after having 

 the cell contents entirely removed, was stained in aniline blue. Tlie 

 whole of the tissue took the colour with the exception of the cuticle, 

 which remained colourless and highly refractive. The inner layer 

 of the hair was stained, but the outer one was not. 



In the process of bleaching, contraction of thin-walled cells often 

 takes place, and tlie cuticle sometimes separates from the cells 

 which it overlays. This has partially happened in the case of this 

 hair ; a separation has taken place at two points, and we have in 

 section what appears as two colourless loops projecting from the 

 blue interior cell-wall, and a moment's examination will suffice to 

 show that this outer layer is of the same nature and continuous with 

 the cuticle which covers the whole of the epidermis. 



I cannot for one moment think that these trichomes are in any 

 sense absorbents, those figured being evidently fitted to serve 

 another purpose. It must be remembered that all surface appen- 

 dages in the pitchers of Sarracenia point in one direction — that is, 

 downward toward its base ; that the first zone is furnished with a 

 considerable number of the strong hairs shown in Fig. 2 ; that then 

 we have another space in which each of the small epidermal cells is 

 prolonged outward and downward into a strong and thickened 

 mammillary process. Next we have a zone with a smooth, highly- 

 polished surface, the remainder of the walls of the deeper portion 

 of the pitcher being furnished with the strong thick-walled trichomes 

 shown in Fig. 5, closely set together and inclined at an acute angle. 

 Now, all these modifications of surface are, without doubt, of value 

 to the plant, and in this direction : that while they will allow an 

 insect to enter and pass down the tube, it is almost impossible for it 

 to return. They thus become veritable insect traps. The pitchers 

 of many species contain fluid, but nothing corresponding to a diges- 

 tive fluid has been detected in them ; so that if the insects which 

 perish in the pitcher are of any value to the plant and afford any 



