412 DR, OTTO STAPF ON THE 
layers, which contain a few minute grains of starch or none at all. Having reached this 
stage, the fruit may be considered mature. 4s appears from the description, it consists 
of the fleshy pericarp and a naked " seed," the embryo proper lying outside the skinny 
covering of the diaphragm, or, what amounts to the same, the embryo-sac. 
VI. INTERNAL STRUCTURE oF THE FRUIT. 
A. The Pericarp. 
The outer epidermis (Pl. 46. figs. 24, 25) of the pericarp consists of isodiametric polygonal 
cells of no great depth, with a very limited number of irregularly interspersed stomata 
(Pl. 46. fig. 25). All the cell-walls, but particularly the side-walls, are considerably and 
often irregularly thickened and the latter perforated by numerous pits. In consequence 
of the somewhat unequal size of the cells, and still more of the unequal thickening and 
the numerous pits, the surface aspect of the epidermis is rather irregular and characterized 
by the unequally crenulated outlines of the cell-lumina. This irregular appearance is 
further enhanced by the frequent presence of silica-bodies (Pl. 46. fig. 26) in the celis, 
which often fill the lumina and make the ceils appear solid. Mr. Boodle was good 
enough to examine for me the epidermis more closely for its silieification. Sections 
treated with phenol in the way described by Grobb (“Anat. d. Epiderm. Gramineenblatt.,” 
in Bibl. Bot. vii. pp. 14—17) or with Eau de Javelle and clove-oil showed that the cells 
containing silica-bodies are arranged in irregular groups of sometimes considerable extent 
and varying shape, and apparently without any definite order (Pl. 46. fig. 26). These silica- 
bodies may be obtained free either by maceration in Schultz’s liquid or by burning. 
'The latter method has the advantage of retaining them in their position, which makes it 
possible to test the appearances obtained by treating the sections with phenol or clove-oil. 
This was desirable, as the silica-bodies show up in these media only on account of their 
particular coefficient of refraction. ‘The silica-bodies are either approximately cubic or 
parallelopipedic or perfect casts of the cell-lumina, or more or less irregular and rarely 
quite solid, minute cavities appearing as pores or rents being the rule. Silicification of 
the cell-walls does not seem to occur, or only to a limited degree. The stomata possess 
semilunar guard-cells, flanked generally by very large subsidiary cells (Pl. 46. fig. 25), 
which are frequently perfectly filled up with silica. The whole epidermis, including the 
euard-cells of the stomata, is completely cuticularized. 
Immediately below the epidermis, the tissue has a collenchymatic (Pl. 46. fig. 24) 
character. This zone is about 4-5 cell-layers deep, the cells gradually increasing 
inwards in size. They are tangeutially slightly flattened and longest in the longitudinal 
axis of the fruit; they contain a considerable amount of plasma and chloroplasts, but little 
(the inner) or no starch. This collenchyma passes inward gradually into a parenchyma 
(Pl. 46. fig. 27) the cells of which are of very considerable dimensions, approximately 
isodiametric, pitted and filled with starch. This is present in ellipsoid or subglobose 
masses, composed of minute globose granules, 1-4 pin diameter, and in isolated more 
or less ellipsoid granules of 6-8 j in diameter. The compound starch-grains, however, 
