472 BOTANICAL GAZETTE [JUNE 
A comparison of the results of potted plants and cuttings of 
the same species, although exhibiting some variation, shows that 
the rate of transpiration is greater in the potted plant. The differ- 
ence is usually greatest at the time of maximum evaporating power _ 
of the air. Under less extreme conditions of evaporation, the 
May 1912. June 1912. July 1912. 
12 24 12 hr 24 24 12 12 24 12 
1.206 », 7 day ¢ 5& 6 8 9 
1.10 g/nr/100 cm2 
g/nr, CoS eae Vac. 
1.00 J F / : corym? 
: ree water : 
x surface 
290 a 8 75. 
men 
-80 * 
Aronia 
70 
af Cham. _, 
60 Vac. . 
coryn.*, 
onan. Larix— 
+. \ 
30 ' Ghanaedaphne Sh8%-+—- 
\ { calyculata 
- % “Larix Picea —--. 
\\<-Ghan. dist.water 
-- Ace o—: 
; “aronia bog water 
30° Temperatur. 
Patti he 
20° Rice | 
100 % Relativw Humidity. 
o% Transpiration of Quttings. 
Fic. 8.—Transpiration of cuttings of Acer Sm Aronia melanocar pa, Chamae- 
daphne calyculata, Larix laricina, Picea mariana, and Vaccinium corymbosum out- 
— sa of cuttings of Chamaedaphne schaiais a bog and distilled water in the 
labora’ 
graphs of transpiration of cuttings accord more closely with those 
of potted plants. From this it follows that one can obtain a knowl- 
edge of relative values under moderate conditions with cuttings, 
but experimentation under extreme conditions of evaporating power 
of the air with cuttings is unsatisfactory. 
From an inspection of all of the summer data, it is seen that 
