1911] OVERTON—TRANSPIRATION AND SAP-FLOW 117 
4. No matter how long the section killed may be, the leaves 
on steamed stems never wither quite so quickly as those cut and 
not placed in water, but under the same conditions of light, tempera- 
ture, and air moisture. 
5. In Cyperus sufficient water to maintain the leaves turgid for 
3-18 days will rise through a stem 15-60 cm. high, with a section 
5-30 cm. long which has been killed with steam. 
6. A certain amount of water is raised through the steamed 
portion, but it gradually diminishes in quantity from day to day, 
until the leaves become air dry (about 11 per cent of their dry 
weight of moisture). 
7. The diminished water supply is partly due to a partial block- 
ing of the vessels with a gumlike or resinous substance, which 
probably owes its origin to the disorganization of the contents of 
the sieve tubes caused by heating the stems. 
8. The withering of the leaves above a steamed portion of the 
stem is probably caused more by the action of deleterious sub- 
stances introduced into them from the dead cells than from lack of 
water. These poisonous substances are probably disorganization 
products caused by heating with steam. 
9. The leaves of rooted plants, grown in nutrient solutions 
containing sterilized decoctions of the same plant, droop in 3-5 days, 
discolor and dry in 7-8 days. 
10. The withering leaves above a portion of the stem killed 
with steam show all the symptoms of dying, namely, rapid loss 
of water after treatment, then a more uniform loss, rounding up 
and discoloration of the chloroplasts, and contraction of the 
mesophyll protoplasts. The leaves are apparently drying, not so 
much from lack of water as on account of the death of the cells 
from other causes. 
11. Judging from the behavior and disorganization of the leaves 
on a stem, a section of which has been killed with steam, it is evident 
that this method of killing the cells is not a satisfactory one in order 
to settle the question as to the relation of the living cells to sap- 
flow. 
12. Killing a portion of the stem by applying wax heated to 
t10° C. causes less apparent disorganization of the cells, less injury 
