Vol. 50 BERL No. | 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
JANUARY, 1923 
The histology of certain orchids with reference to mucilage 
secretion and crystal formation 
Epona L. Smita 
(WITH PLATE 1) 
The subject of mucilage secretion in plants is one which 
has been discussed f-om several points of view. The relation 
of the mucilage to growth, to the prevention of loss of water 
by transpiration, its possible réle as reserve food niaterial, its 
chemical composition, its origin, the processes in connection 
with its formation; all are questions as to plant slimes which 
are still disputed. The relation of raphides to cell mucilage 
is undetermined, although it has long been noted (Frank, Stahl, 
Walliczek, Tschirch and others) that mucilage occurs in cells 
which bear raphides. 
Frank (1867) distinguished plant slimes as gums and muci- 
lages and recognized three general types. First, those from the 
protoplast; second, those deposited by the cell wall; and third, 
those which occur in intercellular canals. He described the 
mucilage in several species of orchids as being derived from the 
protoplast, since, as he observed, there is invariably a thin 
layer of cytoplasm and the nucleus between the mucilage and 
the cell wall. Frank also observed the association of raphides 
and mucilage in the cells of orchids. 
Stahl (1888) considered slime in crystal-bearing cells as a 
reserve food supply, a protection against being eaten by animals, 
and a water regulator. The matter of its origin he does not 
attempt to settle. 
[The BuLLETIN for December (49: 349-407) was issued January 27, 1923,] 
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