Glands of the Plumb agineae. 239 
of papillae, such as occur in Statice articidata , etc., are found 
in connection with the Mettenian glands in a few species of 
Statice. Woronin 1 figures a gland encircled by long tuber- 
culated hairs in .S. sareptana , and the same feature is figured 
by Maury 2 in 5 . elata , and in 5 . latifolia by Volkens 3 . In 
vS. tomentella one finds glands unprotected by hairs, and also 
hairs unassociated with glands. The processes encircling the 
glands in Bourgaei are usually in groups of four, seldom 
more. In *S. pubenda (Fig. 17) they are usually from four 
to six (one only is shown in Fig. 11), and the groups placed 
so closely together as often to touch one another. The 
flower-stalk and both surfaces of the leaf of 5 . pubescens are 
thickly clad with short hairs. 
In Plumbago europaea Mettenian glands are often carried 
up some distance on the epidermis of emergences on the 
margin of the leaf (Fig. 1 2,^). These processes are formed 
of compacted sclerosed elements, the outer ones being seen at 
the apex (Fig. 12 a) to enclose the central one in a spiral 
manner. Their base is usually S-shaped, not straight as 
in the example figured, and tracheides pass up into them 
about two-thirds their length. In general the glands occur 
in longitudinal depressions on the stems of Plumbagos, 
giving rise to a striated appearance when calcium carbonate is 
secreted. Mettenian glands are present on the leaves and 
bracts of all, and the sepals of many, of the species of 
Acantholimon , Statice, Armeria , Plumbago , Ceratostigma , 
Limoniastrum, and Vogelia examined. Their method of 
development is indicated by De Bary in the paragraph already 
quoted. On the margins of the leaves of Plumbago micrantha 
they are seen to arise as single cells which become divided 
into four and sink into the epiderms (Figs. 13, 14). At a 
point in the middle line on the upper surface of a young leaf 
of the same species, in active growth, an interesting series of 
the glands in various conditions of fusion and modification 
was noticed (Fig. 15). 
1 Woronin, loc. cit., Fig. io. ,J Maury, loc. cit., Fig. 40. 
3 Volkens, loc. cit., Fig. 10. 
