44 ’ BOTANICAL GAZETTE [JANUARY 
poisonous solutions from leaking out and injuring the stems below 
the chamber. Such an arrangement has the added advantage of 
allowing the treated portion of the stem to be easily observed 
during the experiment. For 
—. 
have used steam, hot wax, 
and several poisons, treating 
sections of the stems for any 
desired length. As_ poisons 
I have employed saturated 
aqueous solutions of picric 
acid, mercuric bichlorid, cop- 
per sulfate, potassium hy- 
droxid, 1 per cent aqueous 
solution of chromic acid, 4-40 
per cent formalin, alcohol, 
xylol, chloroform, and ZEN- 
KER’s fixing fluid. In every 
instance I have killed both 
shorter and longer stretches 
> 
pared the time required for 
the withering of the leaves, 
and the amount of water ab- 
sorbed and given off, with the 
same data from an untreated 
: : “control plant cut and stand- 
Fic. 1.—Photograph of Cyperus — ing with its base in water. 
having all but one leaf removed and grow 
inan 
the coe oe shows scopic examinations of the 
ranged for steaming a portion of the stem, | Stems above and_ below the 
killed portions, especially in 
the zone between the killed and living region, in order to determine 
if possible whether any visible plugging or stoppage of the vessels 
or other changes above the killed zone occur. Microscopic &* 
aminations were also made to determine to what extent poisons 
penetrated the cells of the stems and the leaves as indicated by 
R 
killing sections of the stem I: 
of the stems, and have com-— 
2 
i 
I have also made some micro- 
