KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 175 
as Mangin has shown, the total absenee of stomata will further 
depress the process of respiration. One cannot avoid the 
suggestion that the production of mucilage may have some- 
thing to do with this difficulty of getting rid of carbonic acid, 
which is necessarily abundant even inside the plant in the 
substratum. Where raphides occur, undoubtedly a deleterious 
excretory product is deposited and held in the mucilage- 
containing cell till the concentration is sufficient to permit 
of the formation of crystals, and from this one might con- 
clude that the object of the mucilage was to absorb the liquid 
. . CO,. 
excretion. It has been ascertained that the fraction rm in 
Neottia and Monotropa is always less than 1, and may be as low 
as *'6, which suggests that some excretion is retained in the plant 
in place of being evolved as carbonic acid*. Alkaloids have 
been shown to occur markedly in raphide-mucilage cells. But 
whatever may be the significance of the mucilage-cells, they are 
not water reservoirs upon which the plant can draw in case of 
need. Volkens completely disposed of this idea by observing 
that the mucilage-cells in desert plants retained all their water 
even when all the rest of the cells had become completely 
dried up. 
APHYLLORCHIS PALLIDA, Blume. 
Blume first deseribed this saprophytic orchid, and in his 
* Orchides de l'Archipel Ind. et du Japon’ an admirable illus- 
tration of the plant is given (p. 52, plate 13. fig. 1). From this 
latter work the following description of the vegetative characters 
of the plant is taken :— f u 
* Radix fibris compluribus vermicularibus carnosis albidis 
villosiusculis horizontaliter extensis composita. 
* Scapus solitarius, pedalis, rectus, teres, pallidus, obsolete 
purpurascenti-striolatus, inferne glaber, vaginulis alternis re- 
motis tubulosis membranaceis, ore oblique truncatis arcte cinctus, 
superne simpliciter racemosus et nonnihil fusco-leprosus x M 
Blume does not mention the occurrence of ehlorophyll in any 
* Aquatic plants have difficulty in obtaining gases essential. And it seems 
possible that the mucilaginous envelope often found on them is for the purpose 
of absorbing or entangling gases, especially carbonic acid. But in this case 
the carbonic acid would be ultimately handed over to the plants under the 
influence of light. 
