SMITH: THE HISTOLOGY OF CERTAIN ORCHIDS 7 
The cell membrane slimes, he says, seem never to play the 
role of reserve food material, but to serve as imbibition mechan- 
isms, a protection against excessive transpiration, a means of 
holding water during the germination of seeds, a mechanism for 
anchoring seeds to a substratum, a protection of water plants 
from animal enemies, and as facilitating gliding in growth. 
The material chiefly used in the present investigations was 
buds and flowers of the orchid Aspasia sp., but more fragmentary 
observations were made also upon the orchids Polystachya 
minuta, Oncidium stipitatum, and Orchis spectabilis. Aspasia 
sp., Oncidium strpitatum,and Polystachya minuta were grown in 
the greenhouse of the botany department at Columbia University. 
Orchis spectabilis was collected May 1, 1921, near Tarrytown, 
In the study of the mucilage and the raphides paraffin 
sections of young buds and mature flowers were treated with a 
variety of staining reagents, mainly the triple stain of safranin, 
gentian violet, orange G.; the double stains, acid fuchsin and 
iodine green and safranin and aniline blue, were likewise found 
useful. Both fresh material and paraffin sections were also stain- 
ed with ruthenium red, which brought out the middle lamella 
clearly. Fresh material was stained with corallin soda, methy- 
lene blue, and various aniline dyes, but all these observations on 
fresh material, while they corroborated the conclusions reached 
with the paraffinsectioned material, were not as satisfactory as the 
study of the microtome sections. The one determination which 
it was possible to make with fresh material and not with fixed 
was the number of crystals in bundles of raphides. When 
corallin soda is placed upon free hand sections of Aspasia sp. 
the mucilage in the cells containing crystals loosens up, making 
it possible to count the number of needles in a cell. Ina large 
number counted the crystals varied from thirty to forty, most 
of the cells having from thirty-two to thirty-five. The variation 
seemed to be independent of the length of the bundles or the 
size of the cell in which they are borne, the small bundles 
having as large a number as the larger ones. 
Cells containing mucilage and raphides were found abund- 
are! distributed throughout the floral parts, longitudinally 
aced with reference to the long axis of the ovary. They were 
