SMITH: THE HISTOLOGY OF CERTAIN ORCHIDS 13 
Plant parts with slimes belonging to the first class are ap- 
parently tubers of Orchis sp., rhizomes of Agropyron repens, 
bulbs of Urginea maritima, bulbs of Allium sp., stem and leaf 
elements of flowers (excepting stamens) of Viola tricolor, Hagenia 
abyssinica, Musa paradisiaca, and succulent plants such as the 
aloe. 
Cell membrane mucilage Kraemer describes as either a 
degeneration of the cell wall or a secondary thickening, as an 
addition to the cell wall or some metamorphosis of it. Plant 
parts with slimes of this class are roots of Althea officinalis 
bark of cinnamon, bark of Rhamnus Frangula, rind of root of 
Sassafras officinale, inner bark of Alnus Frangula, pith and 
medullary ray cells of Astragalus gummifer, parenchyma cells 
of wood and bark of cherry and Acacia senegal, glandular hairs, 
leaf and calyx of Viola tricolor and leaves of Coffea arabica. 
Czapek’s classification of plant slimes as given above is 
probably the most complete and clearly formulated at the 
present time. Lloyd and Miss Stewart report raphides as 
occurring in certain species of cacti which by Czapek are classed 
as having cell membrane slimes. Whether or not cells bearing 
raphides sometimes contain mucilage derived from the cell wall 
is a matter that needs further study. 
CONCLUSIONS 
It is clear from my studies that, as Kohl also showed for 
certain orchids, in the floral organs of Aspasia sp. and Oncidium 
stipitatum the mucilage must originate in the protoplast, since 
the cytoplasm and the nucleus lie between it and the cell wall. 
In these forms mucilage cells were found in the young actively 
growing regions. This mucilage can hardly have the functions 
ascribed to that found in orchid pseudo-bulbs. In all forms in- 
vestigated mucilage and raphides were found associated and 
neither was seen without the other. 
The appearance of the nucleus and cytoplasm in the slime 
cell indicates that it is in a living and active condition. This is 
in sharp contrast to the description which has been given by 
Miss ‘Stewart and others of the appearance of the nucleus and 
cytoplasm in the Cactus slime cells where the nucleus and cyto- 
plasm are in a disorganized state. 
