12 J. M. Macfarlane. — Sarraceniaceae. 



base, which is the only exposed area of the morphological upper leaf surface, outside 

 the pitcher areas. That restriction of stomata to the lower epidermis is not constant, is 

 proved by the abundance of them over the attractive inner lid surface, which is a 

 portion morphologically of the upper leaf surface. 



The inner lid surface that forms, with the margin of the pitcher, the attractive 

 region, shows many glands like the external ones. These are set amid epidermal cells 

 with wavy walls, and amongst them occur stomata in greater or less quantity according 

 to the species. But a conspicuous feature of the region is the bristling mass of down- 

 wardly directed hairs, that vary in size and shape according to the species. Each hair 

 is a strong unicellular thick-walled outgrowth from an epidermal cell, whose surface 

 is beautifully and delicately striated or fluted longitudinally (Fig. 5 Cb). These hairs 

 attain greatest length and strength in S. Drummondii, where each may be \ — \ y 2 mm 

 long. They may be as long but are more slender in S. psittacina, they are strong 

 though slightly shorter in £. purpurea, while S. Sledgei, S. minor, S. flava and S. 

 rubra show decreasing length in the order indicated. By their direction these incline 

 insects to move downward toward the next or conducting area now to be described. 

 The demarcation between the two areas may be indicated by a sharp line across the 

 lower part of the lid, as in S. minor, S. purpurea and S. psittacina, or the two may 

 gradually merge into each other as in S. Drummondii. In S. minor alone, glands 

 identical with all of the above, extend down over the conducting to the upper part of 

 the detentive surface, and though the lower ones do not secrete nectar, such a continuous 

 distribution would suggest that nectar excretion may primitively have been the only func- 

 tion of the glands. In S. purpurea the glands are continued down only to the edge of the 

 detentive surface, while in S. flava and S. Drummondii they form a long descending 

 glandulär tract along the posterior part of the conducting surface. 



The conducting surface in every species has each epidermal cell prolonged into 

 a delicate pointed process with finely striated wall, except in S. purpurea where the 

 process can scarcely be said to exist, or is a mere papilla from the lower part of 

 each cell-wall (Fig. 5 Cd). The resulting imbricated system is of extreme smoothness 

 and evident insecurity to insects, These totter, scramble and usually at length slide 

 off into the deeper parts. Rieh exeretions of nectar may be exuded over this area, 

 specially in its upper limit near the pitcher orifice, and upward along the posterior 

 neck to its junetion with the attractive lid surface. In sharp contrast to the "attractive" 

 epidermal cells, those of the "conducting" surface are straight-walled and nearly qua- 

 drangular. 



Before dealing with the detentive surface, the unique histological relation in S. 

 purpurea Claims attention. In this species the conducting zone is comparatively narrow 

 (\ — % cm wide, Fig. 5 Bb) and along its lower margin its nearly straight-walled epidermal 

 cells gradually assume a wavy or zigzag aspect (0/*), that is continued downward to 

 a considerable depth. Glands become more abundant over this than over the conducting 

 region, and Hooker has therefore appropriately termed it the "glandulär" zone. Its 

 depth is five to eight times greater than that of the zone above. It evidently represents 

 a specialized condition in the upper part of the detentive surface of 8. minor, in that 

 the detentive hairs have been absorbed, though the epidermal cells retain the same 

 zigzag outline and the glands persist. Such a conclusion is strengthened by study of 

 hybrids between S. purpurea and other species. 



The detentive surface is distinguished histologically by the long tapered thick- 

 walled hairs that are attached by narrowed base to some of the epidermal cells. These 

 effectually prevent return or ascent of the animals that have dropped from above. But 

 this more evident relation may incline one at first sight to overlook other peculiarities. 

 Thus in S, minor and S. psittacina the epidermal cells of the upper region are wavy 

 in their walls, lower down they become straight-walled. Glands are also abundant in 

 these over the upper half. In S. psittacina and S. Drummondii stomata are fairly 

 common over the same area, though not found higher up in the tube. In S. purpurea 



