ORIGIN AND NATURE OF THE MUCILAGE IN THE CACTI 
may be readily followed on the addition of water. The lamination in 
tragacanth, seen by Kiitzing {fide Wigand, 1863), is still more evident, and 
is lost only very slowly at ordinary temperatures, while that of Sterculia 
appears to be still more resistant (Maiden, fide Tschirch, Lehrbuch, p. 403, 
vol. 2, pt. i). 
If mucilage cells in this condition are cut open in the making of a section, 
the mucilage swells enormously on the addition of water, oozes out from 
the cell cavity and, carrying the protoplasm and its inclusions with it, 
forms a rope. If pieces of tissue are placed in water, they gradually become 
translucent. This is due to the expulsion of air from the intercullular 
spaces, resulting partly at any rate from the bursting in situ of the mucilage 
cells. This fact may be demonstrated by examining sections of a piece of 
tissue which have lain in water, the sections being dehydrated and examined 
in alcohol. In the case of the medulla of a frond several centimeters thick, 
in which the elongation of the cells had taken place in a direction normal 
to the surface of the frond, it was found that the bursting of the mucilage 
cells had taken place in this direction. This, it was evident, was due to the 
mechanical conditions offered by the web of cell walls and the mutual 
pressures of the cells. Whether such bursting occurs within the plant in 
consequence of local disturbances, resulting in the extrusion of mucilage into 
the intercellular spaces, and possibly filling lacunae (schizogenous or ly- 
sigenous, or due merely to tearing) within the tissues, is not proved, though 
it is rather to be expected, especially when the mucilage cells are large, 
numerous, and mutually contingent. It may be noted in passing that in 
some species of Opuntia and in other genera {e. g., Ariocarpus) there are 
lysigenous canals or lacunae filled with a gummy secretion, but of a different 
nature from that being here considered. 
Effect of Anaesthetics 
Dr. H. A. Spoehr pointed out to me that an abundant oozing of mucilage 
takes place on treatment of tissue with choloroform, ether, etc. I offered 
the explanation that the immediate effect of the reagent was to asphyxiate 
the parenchyma cells by which the mucilage cells are surrounded, upon 
which they give up their water into the intercellular spaces, making it 
possible to hydrate the mucilage cells. This was verified as follows. 
A section was placed without the addition of any medium on a cover 
glass and inverted over vapor of ether in a small glass cell. In the course 
of a minute, the air in the intercellular spaces began to be expelled by water 
escaping from the parenchyma cells. It could then be clearly seen that the 
mucilage cells became more hydra ted, as was proved to the eye by the further 
displacement of the protoplast. Radial strands reaching to the cell wall 
could be observed in the breaking, and the whole mass of protoplasm to be 
further crowded toward the middle of the cell. In some instances the cell 
walls were broken, and the mucilage could then be seen oozing out therefrom 
