32 BOTANICAL GAZETTE [JANUARY 
This progressive effect Dixon attributes to the probable introduc- 
tion into the leaves of poisonous or plasmolyzing substances from 
the dead cells. Three branches of Syringa were placed in water 
and three others in a filtered decoction made by boiling stems 
of the same kind and filtering and cooling the fluid. The stems 
which stood in the decoction wilted its leaves in 2 days, while the 
stems in fresh water wilted their leaves in 5 days. As compared 
with stems set in fresh water, wilting took place much faster 
in those placed in the decoction. In order to show that this effect 
was not due to a clogging of the vessels, the immersed ends of the 
stems were frequently cut away. The injurious properties of the 
decoction remained, showing that wilting was probably not due 
to a clogging of the vessels by comparatively impermeable sub- 
stances, since these would have been removed by the repeated 
filterings. Drxon suggests that it is possible that the application 
of heat in these experiments may to some degree have permanently 
interrupted the water supply by breaking the water columns. 
Ursprunc (35-37) has repeated Drxon’s experiments described 
above, using Impatiens sultani, and has reached the same results. 
Microscopical examination showed him that the vessels at the 
base of the stem were plugged with a brown mass. Upon bring- 
ing a plant which had stood in a decoction into a moist room, 
the leaves again became turgescent. When stems which had 
become stopped by standing in a a decoction were placed in water, 
brought into a moist room. He was unable to find stoppage in 
plants which had been placed in CuCl,. He concludes, therefore, 
that his researches show that the wilting of the leaves is not due. 
to a poisonous action of the decoction, but to the insufficient water 
supply caused by the stoppage of the vessels. He further placed 
a rooted Impatiens plant in a concentrated Impatiens decoction. 
After 2 days, microscopical examination showed that the proto- 
plasm of the root hairs was in a perfectly normal condition. The 
leaves of this plant remained completely turgescent, while those 
of a cut shoot placed in a decoction rapidly wilted. The decoction 
possesses, therefore, according to him, no plasmolyzing substances. 
