tender the Influence of Injuries . 5 1 3 
which had been grown for several months in pots of earth, 
were studied with reference to the growth of young leaves 
and roots when a full-grown vigorous leaf was removed. 
A few cuttings of Salix were prepared according to the 
method used by Kny 1 . 
Phycomyces . — A drop of gelatine containing the proper 
nourishing material was placed on a glass slide, and on the 
gelatine was deposited a single spore of Phycomyces. The 
preparations were kept in damp chambers in the dark until 
one or more sporangium-stalks formed. The damp chambers 
for these experiments consisted of air-tight boxes open at 
one end and two or three centimeters square by five or six 
centimeters long. These were lined on two opposite sides 
with moist filter-paper, and placed over the drop of gelatine 
on which the spore rested. By this means the growth of the 
sporangium-stalk could be observed in the damp chamber 
with the aid of a horizontal microscope. Having determined 
the rate of growth of the sporangium-stalk for a given 
interval, the damp chamber was removed for a moment, 
and the plant subjected to the following treatment: — 
1. One or more of the mycelia were cut at a distance of 
from one to two millimeters from the base of the sporangium- 
stalk under investigation ; 
2. One of two or more sporangium-stalks produced by 
the same plant was cut off ; 
3. The mycelia were treated with a solution of potassium 
nitrate of definite strength. 
In the experiments in which potassium nitrate was used, 
the volume of the gelatine-drop was liable to increase, 
causing an apparent elongation of the sporangium-stalk ; 
hence in these experiments the sporangium-stalks were 
marked with indian ink below the growing zone 2 . 
In all higher plants the growth was measured at intervals 
of three, six, twelve, or twenty-four hours by means of 
a scale divided into half millimeters. For shorter intervals 
1 L. c., p. 276. 
2 Etudes sur ia Turgescence chez le Phycomyces, p. 22, 1885. 
