108 BOTANICAL GAZETTE [FEBRUARY 
The stems were cut off under water and allowed to remain 
there for 6 hours, after which they were quickly transferred to 
the poisons; in each case the base of the stem was immersed for a 
distance of 5cm. They were then transferred to bottles containing 
distilled water, which was covered with a layer of olive oil to prevent 
surface evaporation. Weighings were made daily at noon for 10 
days. 
It will be seen from these tables that more water is evaporated 
from a perfectly dead stem of Cyperus, killed with chromic acid, 
picric acid, or HgCl,, than from a cut plant set in water and kept 
under the same conditions. ‘These substances in some way appar- 
ently alter the constitution of the plant so as to allow it to give 
off more water. As shown by these tables, a plant cut under 
water and kept standing in water continually falls off in the amount 
of water transpired from day to day, and very seldom increases 
the quantity given off on a certain day over that transpired the 
previous day. In the case of poisoned plants the reverse is true. 
Noting the plants numbered II in each table, an increase over the 
first day is shown on each of the two succeeding days. The amount 
of water evaporated on the 8th and oth days exceeds that of the 
7th. Certain other days show increases over the preceding days. 
The plant killed with HgCl, gives off a quantity of water far in 
excess of that given off by plants killed by the other two poisons. 
In table XI plant no. III gives off nearly three times as much water 
on the average per day as does no. I. Another noticeable fact 1s 
that although these poisoned plants evaporate comparatively large 
quantities of water, the percentage of water contained in the plant 
is very much below that in plants which have not been killed. 
This is shown in the last column of table XI; the plant in water 
contains 81 per cent of water, while the one killed with HgCh, 
which gave off the largest quantities of water, contained only 
28 per cent of its dry weight of water. 
General discussion 
As shown by Boru (3), STRASBURGER (30), URSPRUNG (327 
37), Drxon (9-12), RosHarpt (24), and my own experiments, the 
leaves above a steamed or otherwise heated portion of the stem 
