10 SMITH: THE HISTOLOGY OF CERTAIN ORCHIDS 
- 7 observed no knob-like masses at the ends of the raphide 
bundles such as were found in Aspasia sp. Only buds were 
observed in this form. Further study is needed to determine 
the condition of crystals and mucilage in mature flowers. 
POLYSTACHYA MINUTA AND ORCHIS SPECTABILIS 
I can state that raphides associated with mucilage are 
found occurring plentifully in both these forms, but I have not 
as yet studied them cytologically. 
The association of raphides with slime in the cell-content 
slimes has interesting and suggestive implications. Spoehr 
(1917), in discussing the pentose sugars in plant metabolism, 
points out that pentoses and hexoses are the most common forms 
of carbohydrates in plants and that they are transformed with 
ease and in multifarious ways into other compounds in the 
presence of organic salts, acids or alkalis. In the cell which 
produces raphides oxalic acid at least is obviously produced in 
excess and may be concerned in the transformation of sugar 
into a polysaccharide mucilage. Mucilages are generally con- 
sidered to be polysaccharides of sugar, though O’Sullivan con- 
tends that mucilages and gums are not polysaccharides but 
glucoside derivatives of certain organic acids, the acid being 
different for each species producing mucilage. Hare (1911) 
claims that, so far as the opuntias which he analyzed are con- 
cerned, this view seems correct since the amounts of sugar 
and ash obtained were not sufficient to account for the total 
solids, and the residue from hydrolysis contained an undetermined 
organic acid. In this connection it is interesting to note that 
Bourquelot and Bridel (1920) discovered a new glucoside in 
Orchis, loroglossine, and that in eighteen species of native orchids 
which they studied glucosides were found abundantly. It is to 
be remembered, however, that the formation of a mucilage cell 
is a very complex process. It begins with the hypertrophy of 
nucleus and cytoplasm. The raphides appear before the muci- 
lage does. Mucilage formation seems to follow the appearance 
of the raphides in the central vacuole. While the mucilage may 
be formed at the expense of the cytoplasm my preparations 
show most clearly that it is a secretion process and not one of 
mere degeneration. Whether slimes are polysaccharides or 
glucosides the evidence in the floral organs of Aspasia sp. is 
