( 578 ) 
on the various days during the experiment oscillated between 19° 
and 30°. The experiment was stopped on the seventh day. 
Experiment HI. 
Helianthus tuberosus. 
The ice apparatus was fixed round two immediately adjoining 
stems of plants, l 1 / 4 M. in height, on July 14 th 1905 at noon, and 
was filled with ice. In the course of the afternoon the temperature 
of the air space round the stems fell to 0°. No fading could be 
observed; several specimens of the same species, standing next 1o 
the plants experimented upon, served for comparison. Cut leaves, 
hung up on the plants were completely withered in a few hours. 
Nor was withering observable on the experimental plants on fol¬ 
lowing days. 
The temperature in the air space round the stems remained about 
0°. The maximum temperature of the atmosphere in the days of 
the experiment oscillated between 17° and 267 2 °. The experiment 
was stopped on the eighth day. 
2. Ascent of a dye solution in living ancl dead cut branches . 
When cut branches, with a freshly cut surface, are placed with 
this surface in a dye solution, the liquid will in general ascend into 
the branches for some distance, and thus may be easily traced by 
cutting them across at different levels. Various ' elements of the wood 
are then found to have been stained. It matters little whether one 
takes for this experiment living or dead branches, with or without 
leaves; the fluid always ascends in the branches, even when these 
are upside down, i. e. are placed in the solution with their cut 
apex. I generally carried out such experiments with twigs 30— 
40 cm. long; sometimes with pieces of a branch, which had also 
been cut at its upper end. After some days the stain shewed itself 
on the surface of the upper section of these latter branches. 
Although the dye ascends in all branches, the ivay in which the 
various elements are stained is not the same in living and dead 
branches. A sharp difference is observable. 
In comparing living branches with dead ones, it was of course 
necessary to use a harmless stain; the experiments of Stracke . 
investigation of the immunity of the higher plants towards their own 
poison (Dissertation), led me to choose Sdureviolett of Gkcbler. I 
used this stain in a 1 / 1# % aqueous solution. The twigs were placed 
