WAX—GUM—MUCILAGES. 163 
hand, it is soluble in nitric acid with the addition of potassium 
chlorate (though not without decomposition) and in a hot solu- 
tion of caustic potassa. Aniline colors are strongly absorbed by 
it. 
The cell-membrane of the living plant (and to an increased de- 
gree that of drugs) contains, however, beside the deposited sub- 
stances just mentioned, not only the organic constituents of the 
cell which enter it by infiltration, but also abundant amounts of 
inorganic compounds,’ as has already been explained (page 144 
et seq.). These are mostly deposited molecularly (as silicium),* 
more rarely in form of crystals (as in the spicula-cells of Welwit- 
schia mirabilis and the epidermis of Dracena leaves). 
As has previously been mentioned, the cuticle contains not: 
only suberin, but also wax-like bodies. * Occasionally wax 
issues from the membrane, and then forms coatings consisting” 
of granules, small staffs, or crusts. If these are distributed im 
slight amount over the epidermis, the plant organs assume the 
appearance of being covered with hoar-frost (pruinosus), thus 
the leaves of Lucalyptus, Ricinus and Cabbage, Plums, and many 
other allied fruits, and Juniper berries. In some plants, how- 
ever (especially several palms, Anacardiaceew, Myricacee), the 
secretion is so considerable that the wax may be collected in 
large amounts, as, for instance, the Carnauba-wax, from the 
young leaves of the East Brazilian palm, Copernicia cerifera 
Martius. 
The different varieties of wax are esters (compound ethers) of 
the fatty acids; upon saponification they do not, however, afford 
glycerin, but other (monatomic, not triatomic) alcohols. 
The varieties of gum and the mucilages, being closely related 
to cellulose, must be considered in connection with the latter.* 
? The amount of mineral constituents of the membranes is very vari- 
able. The best quality of cotton, dried at 100° C., affords but 1.12 per 
cent of ash. 
* In the siliceous coatings of diatoms, and in the grasses. 
* Compare De Bary, Botan. Zeit., 1871, Nos. 9, 10, 11, 34; and ‘* Ana- 
tomie, ”p. 87 et seq. 
aoe also Valenta, ‘‘ Die Klebe- und Verdickungsmittel.”—Cassel, 
1884, 
