1130 General Notes. 
below descriptions of a few simple devices which I have found of 
much use in my entomological work. 
The most important of these is a device for observing subterra- 
nean insects. This device I have termed a root-cage. It consists 
of a frame holding two plates of glass in a vertical position, and 
only a short distance apart. The space between the plates of glass 
is filled with soil in which seeds are planted or small plants set. 
The width of the space between the plates of glass depends on the 
width of two strips of wood placed between them, one at each end, 
and can be varied according to the necessity of each experiment. 
Outside of each glass there is also at each end a strip of wood for 
holding the glass in place. The strips are fastened by means of 
wedges forced between them and buttons projecting beyond the 
edges of the end pieces, as shown in the figure. It is necessary to 
haye wedges upon only one face of the cage. By making the three 
strips of wood at each end of the cage (one between the glasses and 
one outside of each), of different widths and interchangeable, the 
width of the space between the glasses can be easily varied. imme 
diately outside of each glass there is a piece of blackened zinc which 
slips into grooves in the strips at the ends, and which can be easly — 
removed. When these zincs are in place they keep the soil dark. 
In the first lot of root-cages that I had made holes were bored in 
the bottom to provide for drainage. But the danger of the escape 
of insects through these holes has led me to depend on the pec 
of the water through the cracks between the glass and the wooe 
A layer of very coarse sand one inch in depth at the bottom of the 
space between the glass facilitates drainage. 
