116 BOTANICAL GAZETTE [FEBRUARY 
branch when the leaves were dead. A cooked and dried oak twig 
about 25 cm. long was then set in a tube with a manometer, with 
water above and mercury below. The twig was able to raise 
mercury 70.3 cm. high. In another somewhat modified experi- 
ment with a Thuja twig the mercury rose to 86.4 cm. 
ASKENASY believes that the suction power exhibited by dead 
leaves is explainable by the fact that the water evaporates from 
the outer surface of the cell walls of the mesophyll into the inter- 
cellular spaces, and is supplied from within through the protoplasmic 
lining. He thinks that the imbibitional force of the wall is greater 
than the osmotic power of the cell sap. He further adds: 
Da diese Imbibitionskraft durch den Tod der Zelle im Allgemeinen nicht 
beeintrichtigt wird, so ist es kein Wunder, dass auch tote Zellen, wenn sonst 
die Verhiltnisse giinstig liegen, im Stande sind, das an ihnen verdunstende 
Wasser ebenso hoch zu heben wie lebendige 
There can be no doubt that cell walls possess a great attraction 
for water. As Dixon (10-12) points out, the submicroscopical 
spaces occupied by the imbibed water in the cell walls of the 
mesophyll are intensely minute capillaries. It seems quite pos- 
sible that these poisons may in some way alter the character of 
_ these passages, and so affect the amount of water imbibed by the 
walls and also the amount of water evaporated by the surfaces 
of these cells. It is certain that in the case of plants poisoned 
throughout, the elevation of the water in the stems, and its evapora- 
tion from the leaves in larger quantities than normally occurs in 
living plants, depend purely upon physical processes. 
Summary 
1. Stems of Cyperus cut and placed in water wither sooner than 
when a certain portion, not to exceed 20 cm., has been killed by 
steam. 
2. When 20 cm. of the stem are killed by steam, the leaves 
wither in about 8 days, that is, in about the same time as the 
control plants. 
3. The longer the portion of the stem killed with steam, the 
sooner the leaves above wither and dry. When 25 to 30 cm. 0 
the stem are killed with steam, the leaves wither in 3~-5 days. 
