1911] OV ERTON—TRANSPIRATION AND SAP-FLOW 61 
above such steamed regions remain turgescent for a period of 5-18 
days, depending on the length of the stretch killed. Comparing 
the results of table VII with those of table IV, we see that in killing 
by hot wax, the longer the killed section, the sooner the leaves 
above wither. On the other hand, this method of applying heat 
does not cause withering and final drying nearly so quickly as 
steaming. There can be no doubt that the treated portions were 
killed by the hot wax. Microscopical examination indicates that 
the cells are dead, but that there is much less disorganization caused 
by this sort of treatment than by using steam. These stems do 
not show so much initial plugging of the lumina of the vessels, 
although the ducts finally become much discolored. As the table 
shows, leaves may remain turgid for a period of 5-23 days (or longer 
in case 5 cm. are killed), depending on the length of the stretch | 
killed; while the maximum time of turgidity for stems with a sec- 
tion killed by steam did not exceed 18 days. To compare specific 
cases in table IV, nos. 14——S (1908), 50—S (1908), 5—S (1909), 
24—S (1909), and 63—S (rg10) each had 1o cm. treated; the leaves 
on these plants withered in 8 or ro days. In table VII, nos. 3—W, 
4—W, and 7—W each had the same distance killed, but the leaves 
did not dry until 14-34 days thereafter. They lasted nearly three 
times as long. 
I have also determined the actual amount of water transpired 
by the leaves of a plant before and after treatment with the hot 
wax, just as was done in the case when steam was used (see tables 
Vand VI). The average transpiratién for each 24 hours for 5 days 
was determined, then ro cm. of the stem were killed and the observa- 
tion was continued. The results appear in tables VIII and IX. 
The daily loss in grams is shown in the second column in each table. 
Observations were made in order to compare the effect of tempera- 
ture and weather conditions on the amount of transpiration. The 
average daily temperature was obtained, as before, by taking the 
average of the temperatures as recorded by the self-registering ther- — 
mometer. 
It will be noted that there is an increased amount of water 
transpired the first 2 days after treatment with the hot wax, 
although the temperature was lower than it was the first 2 days 
