32 Russell— Comparison of the Structure of Hybrid 



Glands 



The structure of the glands on the pitcher surfaces, spoken 

 of in this paper, is in general identical. Brief descriptions 

 have been given, and several figures by Goebel (32), Fenner 

 (31), and others. There are above, appearing on the epidermal 

 surface, two central cells, heavily thickened, surrounded by 

 from 4 to 6 companion cells. The cap cells, or the central 

 cells, are wedge-shaped, and run down between the surrounding 

 cells into the second or third tier of cells constituting the gland. 

 The whole structure is then flask-shaped, and is composed of 

 16 or more cells, extending down into the mesophyl, but sep- 

 arated from that tissue by a cuticular lamella, with reticulate 

 thickenings. The cap cells mentioned above stain differently 

 from the surrounding cells, taking gentian-violet stain deeply, 

 while the surrounding cells absorb safranin. Further, the 

 surrounding cells give a marked positive reaction for tannin, 

 with ferric iron chloride. In view of the above, it seems very 

 probable that the cap cells are the secretory cells, and that the 

 tannin present is the source for the sugar in the secreted liquid. 



Though the structure of these glands has been considered 

 briefly, there has been but one paper tracing their develop- 

 ment — that of Fenner (31). He describes their origin from 

 an epidermal initial cell which divides longitudinally and trans- 

 versely to form a two-tiered group of cells. But next he con- 

 siders that a split occurs between the upper cells, and that this 

 split deepens until it involves the lower layer also. Into this 

 "pit," he says, the secreted honey is poured. The writer finds 

 no evidence of any such splitting. In fact the pit he mentions 

 occupies the position of the cap cells. What occurs is this: 

 The gland initial divides longitudinally and transversely as 

 indicated, forming a two-tiered structure of four cells, two 

 above, two below. From the two upper cells are cut off two 

 smaller cells after the fashion of guard cells. These two cells 

 are the cap cells. The two upper cells redivide to form the 

 4-6 surrounding cells. The second tier below divides trans- 

 versely and longitudinally into 8-16 cells to form the second 

 and third tiers. While this growth is going on, the two cap 

 cells are pushed to a central position, and are flattened against 

 each other until they assume the characteristic wedge shape (32). 



