APPENDIX 579 
\ \ LZ \ yl 
WSZETISZIZV 
\KSEECRY 
Frost’s Plate Counter. 
Each of the larger squares represents an area of 1 sq em. The figures 60 and 40 indicate the 
number of square centimeters in the circles bounded by the respectivelines Each sector 1s 
one-tenth the area of its circle. 
Department of Bacteriology, University of Ilinois. 
