562 Balls . — Temperature and Growth. 
The end of a long plate of thick copper lies under the end of the large 
glass slide which carries the water-bath. The outer end of this plate is 
supported on a stand. Injury to the microscope stage by the inner end is 
prevented by resting it on a sheet of asbestos, through which, as well as 
through the copper plate, a hole is bored for illumination of the object. 
Cortt~r&l Couple ttj wax u/iB th tr*m om iTzr 
Front cl lv cl, 1 o 77 
Fig. 2 a. 
C over - Glass. 
Col tort o, a 7 nit r 
Fig. 2 c. 
Fig. 2 d. 
Fig. 2. a. Control-couple plate, with thermometer. 
b. Plan of control- couple plate showing connexions. 
c . Culture chamber. 
d. Plan of cover-slip showing locking- wire. 
Below the copper plate a small gas flame stands on the work -bench, and 
this flame can be moved to any point between the microscope and the 
outer support ; the heat from this flame is conducted along the copper 
plate to the stage, and there heats the water in the bath, which in its turn 
heats the medium in the beaker, and the convection currents in this flow 
