816 Report OF THE DEPARTMENT OF ENTOMOLOGY. 
brass curtain rings proved very satisfactory. Thin circular cover 
glasses, the same as used in microscopical work, were placed 
over the rings and held in place by paraffin. Enough paraffin 
was always used to entirely cover the ring. To admit air small 
holes were made with the point of a fine needle, through the 
paraffin, just under the cover glass. Plate LII, Fig. 2. 
In our studies sound apples were found very convenient. A 
single female could be isolated and her offspring easily counted, 
or a single larva could be kept within narrow limits for close 
observation, 
