Senecio precox, D.C., from Mexico. 39 
bei A7einia articulata), und die Wassermengen, welche in dem 
Vegetationskorper einer solchen Pflanze aufgespeichert sind, 
sind teilweise recht betrachtliche.” 
Histology of the Root.—The smallest roots (;1,-inch diameter) 
show about twelve concentric rows of cork with the outer 
wall of each cell somewhat bowed. The cortex consists of 
at least six concentric rows of rounded parenchyma cells, 
which when stained with Kleinenberg’s alcoholic hematoxylon 
take a deep purple color. The central stele is diarchic, and 
differs little from that of an ordinary dicotyledonous root. 
The older roots show considerably more cork, and the outer 
layers have begun to exfoliate. Such roots soon exhibit the 
modifications, which take place in the increased thickening of 
dicotyledonous roots,namely the gradual shifting of the radially 
arranged phloem until it occupies an outside position with ref- 
erence to the wood. When this growth is completed, normal 
increase proceeds as in the stem. Balsamic reservoirs are seen 
in two positions in the exocortex and endocortex of the roots. 
Histology of the Stem—The cork (C Text Fig.), in com- 
parison to the diameter of the stem, is not so plentiful as in 
the roots. It is formed from a phellogenetic layer just out- 
side of the green phelloderm. The green portion of the cortex 
shows quite large, light green chlorophyll grains. The spaces 
in the cortex, which are formed lysigenously, contain a fluid 
which, subjected to the following tests, seems to indicate that 
we have to deal with a balsam, rather than a true resin. Abso- 
lute alcohol dissolves the exudate without a sediment. Tur- 
pentine dissolves the clear, amber-like substance with a slight 
granular sediment. Ether dissolves it without a sediment. 
The exudation is insoluble in cold, but soluble in hot, potash, 
leaving a slight cloudy precipitate. Aqueous solution of 
acetate of copper was used upon several sections, exposed to 
its action for five or six days, without obtaining the emerald- 
green resin reaction. The smell, suggesting the presence of a 
volatile oil seems also to point to the exudate, being a balsam. 
