The mucilage must be acidulated with hydrochloric acid before dialysing, to set free the gummic acid.
An orchis found in the mountain yields the dried tuber which affords the nutritious mucilage called salep; a good deal of this goes to India.
Such filaments may not give rise to mucilage on the I.
As in other cell-walls, so here the older membranes may be altered by deposits of various substances, such as resin, calcium oxalate, colouring matters; or more profoundly altered throughout, or in definite layers, by lignification, suberization (Trametes, Daedalea), or swelling to a gelatinous mucilage (Tremella, Gymnosporangium), while cutinization of the outer layers is common.
The seeds when placed in water for some time become coated with glutinous matter from the exudation of the mucilage in the external layer of the epidermis; and by boiling in sixteen parts of water they exude sufficient mucilage to form with the water a thick pasty decoction.
Cryptomonas, when dividing in a mucilage after encystment, recalls the condition in Gloeocystis.
The occurrence of a plentiful mucilage in many freshwater forms is, however, doubtless a provision against desiccation on exposure.
The multicellular species consist of filaments, branched or unbranched, which arise by the repeated divisions of the cells in parallel planes, no formation of mucilage occurring in the dividing walls.
In their reactions the different kinds of mucilage present differences; e.g.
The mucilage may also form an embedding substance similar to that of Chroococcaceae, in which the filaments lie parallel or radiate from a common centre (Rivulariaceae).