Ipomoea paniculata . 279 
Nepenthes. In some of these, more especially the * alluring 
stem- and leaf-glands , 5 the analogy of the general structure is 
very noticeable ; and as the author points out, it closely 
resembles that of animal glands. Speaking of the alluring 
leaf-glands he says 1 , ‘ when placed on the outer surface of the 
lid or pitcher they much resemble attractive lid-glands, with 
the addition that a covering flap of epidermal tissue varying 
in extent grows over them, or more commonly even, like 
certain attractive lid-glands (N. Lowii , N. laevis , N. Pervillei ), 
they are so encircled and closed in by the epidermal covering 
that the gland becomes “ perithecioid,” and the sugary 
secretion exudes from a small circular orifice of the epidermis. 
On tendrils and on the under surface of the lamina the peri- 
thecioid form is characteristic, and it attains its most gigantic 
proportions on the tendril of N. bicalcarata , where, owing to 
rapid growth of the tendril, the gland-orifice becomes slit-like, 
and the gland-tissue may be one-eighth of an inch in length 
and one-sixteenth of an inch in width . 5 In the glands of the 
stem, ‘the three layers of gland-cells all show clear finely- 
granular protoplasm, and a vascular diverticulum ends beneath. 
But in all cases the diverticulum is separated from the gland- 
tissue by two layers of bead-like cells, which in position and 
function seems to correspond to the membrana propria of 
animal glands. The similarity of this to a simple animal 
gland in shape, structure, excretion, and vascular supply is 
obvious, and need not further be dwelt on. The resemblance, 
however, is even more striking in the pedicel-gland of 
N. bicalcar ata, . . . where a tendency to branching of the gland- 
tissue occurs . 5 Here, then, we have the two layers of clear 
cells which Macfarlane compares to the membrana propria , 
the vascular diverticulum just below the gland, the covering 
epidermal flap and perithecioid arrangement, and the branch- 
ing of the gland-tissue, just as in the gland of Ipomoea. 
Development of the Gland. In order to investigate the 
origin of the gland and its subsequent development, sections 
1 Observations on Pitchered Insectivorous Plants (Part II). Annals of Botany, 
Vol. vii. p. 429. 
