Glands of the Plumb agineae. 247 
are less numerous at the apex than at the base. The stout 
basal cells are often more than four in number (Fig. 34, b\ and 
the glandular portion ranges from *12 mm. to *18 mm. across. 
The stalked glands on the exterior of the calyx of cultivated 
species, e. g. P. capensis and P. rosea (Fig. 36), are very 
familiar objects. They have been studied by Maury 1 , Mar- 
tinet 2 , and others. The extreme viscidity of the mucilaginous 
secretion has been remarked by many authors. In P. zeylanica 
the entire rachis is thickly' studded with active glands like the 
calycine ones, but more minute. The glands of P. rosea are 
spherical, bright-red, and formed of very numerous polygonal 
cells. When fully developed they are very opaque, and their 
whole structure remarkably tough. The stalk penetrates a 
considerable distance into the fully-formed head, so as to make 
the base of the gland dome-shaped or conical. This condition 
is very pronounced in P. scandens (Fig. 37). Spiral vessels pass 
up a greater or less distance into the stalks. Seeing, how- 
ever, that vessels are found penetrating simple emergences, 
e. g. in Ceratostigma , etc., no special significance attaches to 
them in connection with the glands. Younger and smaller 
external glands are fairly translucent. The stalks of almost 
sessile glands are composed of a few comparatively large cells 
(Figs. 38). Minute glands (• 12 mm. in diameter) nearly sessile 
were found, having their base formed of four cells. 
Maury has figured 3 sessile glands on the inner face of the 
sepals of P. capensis . The same occur also in P. scandens 
(Fig. 68), P. europaea , P. zeylanica (Figs. 40, 41), and P. rosea 
(Figo 70). Their basal cells are usually four in number, but 
very often two (P. rosea). Sometimes the basal cells are deep 
as in P. scandens (Fig. 68, b), and in all cases they support 
numerous very thin-walled secreting cells. These glands are 
evidently homologous with those similarly situated in Vogelia. 
Their homology with the stalked glands on the exterior of 
the calyx, traced through the smaller and almost sessile ones 
there, cannot be doubted. Further, the sessile glands do not 
1 Maury, loc. cit., p. 55. 2 Martinet, loc. cit., p. 195. 
3 Loc. cit. (PI. V, fig. 62). 
