ON THE ANATOMY OF DRUGS. 
461 
intelligible description that would guide an observer, but, in general terms, it 
may be stated, that whilst in some species the cells composing the sheath are 
rounded and equally thickened, in others they are much elongated in the direc¬ 
tion of the radius, and liave the secondary deposit unsymmetrically arranged ; 
besides which, the size of the cells and the extent to which secondary deposit 
has taken place within them are points which must be noticed. 
Another Endogenous product is Ginger, the dried rhizome of Zingiber offici¬ 
nale^ but it presents few structural peculiarities that need be dwelt upon. Its 
transverse section shows a central woody portion, separated from the outer 
cortical ring by a narrow line representing a sort of vascular sheath. Both the 
outer and inner portions consist chiefly of ordinary cellular tissue (parenchyma) 
traversed longitudinally by fibro-vascular bundles ; but whilst these bundles are 
sparingly distributed through the outer layer, they constitute an important 
element in the central column. The cells are loaded with elongated, oval, or 
truncate starch granules, having strongly marked lines of deposit. At intervals 
may be seen dark-coloured cells filled with the resin to which ginger .owes its 
pungency and flavour, and these are to be observed more plentifully in the 
narrow portions at the base of each lobe of the race. The vascular sheath con¬ 
sists of thick-walled cells elongated in a direction parallel with the growth of 
the rhizome, and has, inserted at intervals along it, little groups of two or three 
large spiral vessels. 
The Sweet Flag {Acorus Calamus)^ so well known as a water plant, especially 
in the east and south of England, yields a rhizome having many structural 
differences from that just described, fitting it for the different external con¬ 
ditions under which it grows. Yet at first sight there is considerable likeness. 
In their transverse sections we see the same sort of central column, a similar 
outside zone, consisting almost entirely of cellular tissue, and, as in ginger, a 
narrow sheath separating the two. The first and chief difference consists in the 
- very loose spongy character of the tissue, giving lightness to the rhizome. 
Whilst in ginger we have the cells closely packed and taking an angular form, 
so as completely to fill the space, in Calamus they are small and rounded and 
joined together in lines, with the seeming object of enclosing the largest pos¬ 
sible number of air-canals consistent with due firmness of texture. At the 
angles formed by the meeting of two or three of these lines of cells are situated 
certain cells of somewhat different appearance from the rest, and often a little 
larger, which are the reservoirs for the essential oil that gives the fragrance for 
which the rhizome is valued. The fibro-vascular bundles are larger than in 
ginger; and though a few may be found in the outer zone, the principal number 
are inserted immediately within the border of the central column. The sheath 
is cellular rather than vascular in structure. 
Professor Bentley’s paper on the “ Adulteration of Saffron renders any 
allusion to the structural characters of this product unnecessary; and the fear of 
wearying those we design to interest induces us to omit any description of the 
fruit and seeds of Cevadilla, Colchicum, and Cardamom, but we may be allowed 
a few words concerning Vanilla. 
Few Natural Orders of plants are so anomalous in the disposition and struc¬ 
ture of their various organs as the Orcliidacess; and this is not only true of their 
conspicuous parts, but to a great extent also in those requiring the microscope 
for their elucidation. Let any one wishing to satisfy himself of the fact obtain 
a leaf of almost any of the common stove orchids {Oncidium^ Saccolabium^ or 
other) and examine a thin slice cut out of any part of it with a moderate mag¬ 
nifying power. The chances are he will find many large cells differing from 
* Pharm. Joxirn. 1866, 2nd ser. vol. vii. p. 452. 
