PROPERTIES OE THE LEAP OP DIOH2EA. 
11 
investigating the successive states (tension differences) which present themselves after 
excitation, with reference to their duration and their time-relations with other 
phenomena or processes which precede or accompany them ; or (D) for exciting, or 
otherwise temporarily modifying the physiological conditions of the organ. 
The appliances used for these several purposes in the case of the leaf of Dionsea are 
as follows :— 
A. Means of maintaining favourable conditions of temperature , dc., during the 
period of observation. —By preliminary experiments it was ascertained that the 
conditions most favourable to the activity of.the leaf are, that the temperature of 
the leaf should he from 32° C. to 35° C. and that the air should he nearly saturated. 
For the maintenance of these conditions the plant is placed in a chamber of the 
following construction (fig. 1). 
Pig. 1. 
Tlie Warm Chamber. 
The sponges which serve to keep the air saturated rest on the glass plate which covers the 
sliding floor. On this glass plate the plant, electrode holders, &c., rest. To withdraw them, 
the floor is made to slide out along the rails. The upper part of the tube of the regulator 
is seen on the right side. (From a photograph.) 
The chamber measures 47 centims. wide and 40 centims. from back to front, and is 
26 centims. high. It is made of japanned tin plate. Its top, bottom, and sides are 
double, and separated from each other by a closed cavity of 1 centims. in width, 
which is filled with water. Its front and back are closed by panes of glass which 
slide up and down in grooves. The water contained in the bottom, sides, and top is 
heated by an ordinary gas burner, 3 inches below the bottom, along which, and up 
one side a chimney, 2| centims. by leads. The temperature of the water is 
governed by an automatic regulator of the form described by Mr. Page in the Journal 
c 2 
