96 PHARMACEUTICAL BOTANY 
in the chromatophores instead of starch as the first visible product 
of photosynthesis. In higher plants it is generally found in 
storage regions, such as the parenchyma of seeds, fruits and the 
medullary-ray cells and the parenchyma of barks, roots and 
rhizomes. 
19. Waxes.—These are esters of fatty acids which differ 
from fixed oils and fats in not forming glycerin when saponified, 
but rather certain of the higher monatomic alcohols which are 
insoluble in water. 
The characteristic bloom on the epidermis of fruits of 
junipers, plums and grapes and the glaucous surfaces of many 
leaves are due to waxy coatings. Three types of waxy covering 
occur on plants. ‘The most common type consists of densely 
crowded granules as seen on the leaves and stems of many lilies, 
grasses and irises. On the nodes of the sugar cane the covering 
assumes the form of a layer of vertical rods, rolled or hooked at 
their distal ends [Fig. 68(3)]. On the leaves of the houseleek 
(Sempervivum) and the wax palms it occurs as a crust interspersed 
with cracks. On the fruits of the wax myrtle and bayberry this 
wax crust is secreted by glandular emergences. 
Wax serves as an effective control over transpiration by the 
epidermis. It also gives rigidity to the epidermis, lessening the 
compression and distortion of subjacent parenchyma which is 
apt to occur from its contraction during loss of water. 
The more important vegetable waxes of commerce are 
Carnauba Wax, from the leaf buds and young leaves of Copernicia 
cerifera, the Brazilian Wax Palm, Myrtle or Bayberry Wax from 
the fruits of Myrica cerifera, M. carolinensis and M. xalapensis, 
and Japan Wax from the fruits of Rhus succedana, R. vernicifera 
and R, sylvestris. 
20. VoLaTILE Ons.—These are volatile odoriferous princi- 
ples found in various parts of numerous plants which arise either 
as a direct product of the protoplasm or through a decomposition 
of a layer of the cell wall which Tschirch designates a “‘resino- 
genous layer.” They are readily distilled from plants, together 
with watery vapor, are slightly soluble in water, but very soluble 
in fixed oils, ether, chloroform, glacial acetic acid, naphtha, 
alcohol, benzin and benzol. They leave a spot on paper which, 
