14 J- M. Macfarlane. — Sarraceniaceae. 



transition from the "glandulär" to the "detentive" surface is very sharp, the wavy. cells 

 and abundant glands of the former suddenly changing into the straight thick-walled 

 cells devoid of glands in the latter. Though the transition is a gradual one in S. 

 minor, the writer considers that the upper half of its detentive surface is distinct from 

 the lower, and that the glandulär area of S. purpurea is a modification from the 

 former. Striking confirmation of this view is got from study of hybrids between S. 

 purpurea and S. flava. Thus natural specimens of this hybrid, first described as S. 

 Gatesbaei, as well as artificial hybrids of the same parentage, show a blending of wall 

 outline, glands and hairs in the glandulär zone, and a rather sudden transition to the 

 straight-walled cells of the detentive zone. 



The lowest part of the pitcher cavity, to the depth of 2 — 4 cm, is usually devoid 

 of hairs, as pointed out by Goebel, but the epidermal cells otherwise exactly agree 

 with those of the typical detentive surface. The presence of hairs here would be 

 superfluous. There seems no good reason either for regarding it as a special absorptive 

 zone, so that the application of a particular name to it seems scarcely necessary. 



The surface histology of laminar phyllodia does not differ from that of the lower 

 external areas of pitchered leaves. But the scale or autumnal leaves deserve some 

 notice. In these numerous glands occur alike over upper (inner) and lower (outer) 

 surface. Stomata are absent over the upper epidermal surface in all the species, they 

 are sparingly present over the lower (outer) epidermis in S. purpurea, but are absent 

 in most. Such anatomical details favor the view that scale leaves are merely greatly 

 reduced pitchered leaves. 



The internal histology of the leaf is instructive, owing to the peculiar laminar 

 modifications that have developed. The petiolar sheath shows an irregulär crescent of 

 vascular bundles that have run out from the rhizome. They exhibit typical collateral 

 structure, have strong stereom patches without and within, and are embedded in a 

 loose starch-storing cellular tissue that is surrounded by the epidermis. Higher up in 

 the cylindrical part of the petiole, the bundles Orient themselves so as to form a dis- 

 continuous circle of bundles on the inner side of the chlorophylloid cortex, and an 

 irregularly disposed central series. Though varying in size all retain similar structure, 

 except that the stereom patches become stronger and more prominent. At the level 

 where the laminar wing begins to protrude two sets of bundles run out into it, and 

 these are so disposed that their xylem-patches face each other, while their phloem- 

 patches face toward the exterior. Slightly higher up the midrib bundles arrange themselves 

 into a loose ring, while the cellular tissue that they enclose becomes hollowed out by 

 the invaginated epidermal tissue that lines the pitcher cavity. With increase in width 

 upward of the laminar wing additional double sets of vascular bundles pass into it 

 from the now hollowed-out midrib. Those which have already entered may also branch 

 lengthwise. A structural condition is thus developed that is shown in Fig. 5 A. The 

 chlorophylloid tissue is mainly massed beneath the outer epidermis, the subjacent cellular 

 tissue is highly spongy, and its cells störe starch. Next to the epidermis of the pitcher 

 cavity are 3 to 4 layers of transversely elongated rather thick-walled cells of relatively 

 large size. These contrast strongly with the small epidermal cells, each of which while 

 it may be thickened along its lateral walls, shows a thin delicate wall against the pitcher 

 cavity over the lower detentive area. A peculiar structural modification of the upper 

 part of the pitcher is seen in S. minor, S. Drummondii, and less sharply in S. psittacina. 

 Toward the top of the pitcher occur clear white circular areas, similar to those of 

 Darlingtonia. In S. minor these are mainly confined to the posterior part of the 

 orifice and base of the lid. In the two remaining species they are formed abundantly 

 round the orifice and on the lid or hood. Each area consists of external and internal 

 epidermis that are almost apposed owing to thinning-out of the mesophyll. External 

 and internal hairs and glands are absent over each area, but round it the hairs are 

 so disposed that each is a fenced enclosure open only on one side, for while the lower 

 and upper hairs are directed longitudinally, the lateral ones point obliquely towards 



