14 Russell— Comparison of the Structure of Hybrid 



fewer — io-ii. The glands present have a tendency to be 

 distributed along the strong ridges above the veins, especially 

 in 5. flava. Averages of counts from the surface between the 

 veins run about .5 gland per field, while on the veins 2-3 glands 

 appear in a field. In 5. purpurea, where the veins are not so 

 emphasized, the glands are equally distributed over the outer 

 surface, and there are two to a field. In 5. Catesbaei there 

 are fewer glands than in S. flava — one to a field, though here 

 there is a slight tendency for the glands to be more numerous 

 over the veins. 



The ridges spoken of above are formed by the reinforcement 

 of the larger bundles on their inner and outer faces with a deep 

 sclerenchymatous development. Above such bundles the sub- 

 epidermal and epidermal layers become thickened enormously, 

 so that the whole thickened area stands out above the sur- 

 rounding epidermis. The ridges are very marked in 5. flava, 

 are not shown in S. purpurea, and are fairly conspicuous in 

 5. Catesbaei. 



The epidermis above the bundles undergoes a peculiar trans- 

 formation. In S. purpurea, the wavy walled epidermal cells 

 become elongated above the bundles. In 5. flava, the epi- 

 dermal cells are elongated, straight walled cells, much thick- 

 ened. S. Catesbaei has these cells elongated slightly, heavily 

 thickened — in fact about intermediate in character. Along 

 these lines of cells there are no stomata, nor hairs; therefore 

 they form the easiest paths which the insects can pursue up- 

 ward toward the rim of the pitcher. 



Conducting Surface 



Below the lid surface in all forms, the epidermal cells become 

 gradually polygonal in shape, and the hair processes become 

 shorter and sharper. Every cell becomes prolonged into a 

 pointed projection directed downward. The cells thus form 

 a scale-like slippery covering for the inner pitcher surface to 

 a varying depth. In 5. purpurea it forms a narrow band, 1-2 

 cm. wide; while in S. flava and 5. Catesbaei it extends over at 

 least one-half of the pitcher depth. 



The conducting cells of these three forms are interesting 

 in length relation. In 5. purpurea the tip process is but little 

 more than a knob (PI. V, fig. 22) and the cell measures .05 mm. 



