GUM—MUCILAGES. 167 
nella fenum grecum ( fenugreek seed), present an illustration of 
the formation of mucilage occurring in the inner tissue, not in 
the epidermis.’ 
In leaves, mucilage appears to be formed but rarely in larger 
amounts. A very remarkable example of this character * is 
presented by the Buchu leaves from Barosma crenulata Hooker 
and other species. 
But mucilages are also formed in the plant, apparently with- 
out this direct participation of the membrane. They then fill 
either all the cells of the tissue (Irish moss), often in combination 
with starch (Sphwraococcus lichenoides), or are confined to indi- 
vidual cells, which are often distinguished by their shape and 
size (cinnamon, elm bark, salep *), or, finally, are given off by 
intercullular receptacles of secretions (Cycadew). Even the gum 
which exudes upon wounded places, for the purpose of closing 
the vessels—and which, therefore, serves a physiological pur- 
pose—is not formed through a conversion of the membrane into 
gum, but is secreted by the same in the form of drops * (see 
above). 
The designation, bassorin, has injudiciously ° been trans- 
ferred to a part of the mucilages. Solutions of plant mucilage 
are not only precipitated by basic acetate (subacetate) of lead, 
but also by the neutral acetate (sugar of lead). Plant mucilage 
from its various sources presents, however, in its behavior to 
water, all gradations, from complete solubility to mere swelling, 
accompanied by but extremely slight solution. For the pur- 
pose of microscopical examination of tissues containing mucilage, 
those liquids are therefore useful which act to a less extent upon 
1 Fliickiger, ‘‘ Pharmakognosie,” 1883, 934. 
? Flickiger, Schweizerische Wochenschrift fiir Pharmacie, 1873, p. 
435; Fliickiger and Hanbury, * Pharmacographia,” 1879, p. 109; Radlko- 
fer, “‘Sapindaceen-Gattung Serjania.” Munich, 1875, 100. 
8 Berg’s ** Atlas,” Plate XXIII, Fig. 57. 
4 Frank, ‘‘ Berichte d. deutsch. botan. Ges.,” IT. (1884), 322. 
5 Injudicious in so far as under the name of Bassora Gum different 
and not accurately known varieties of mucilage, similar to tragacanth, 
have been grouped together; the expression bassorin is, therefore, not 
capable of precise definition; and should be abandoned. © 
