264 THE AMERICAN NATURALIST. [VoL. XXXII. 
Plotting the chirps per minute as ordinates, and temperatures 
(degrees Fahrenheit) as abscissa, we obtained a series of points 
whose maximum deviation from a straight line was only about six per 
cent. From this we deduced the relation 
T= 60 +> 22, 
where T stands for temperature, and N for chirps per minute. For 
temperatures between 6o and 8o this equation is accurate within one 
CHIRPS PER MINUTE. 
~ 
È 
80 
6o 
40 
56° 58° 60° 62° 6. My 66° 68° 70° 72° 7 4 76° 78° 80° 82° 84° 
TEMPERATURE DEGREES FAHR. 
Figure showin; 
ure and rate of chirping. The solid 
straight line conforms to the pte aye eg as curved line is evidently somewhat 
closer to the observed facts. 
or two degrees. Below 60, however, the insects chirp at a somewhat 
faster rate than would be expected from the formula, and consequently 
the calculated temperatures would be two or three degrees too high. 
This deviation shows that the actual relationship between the rate 
of chirping and temperature cannot be exactly expressed by a straight 
line, as in our diagram, but should rather be expressed by a curve 
approximating that shown in the figure by the dotted line. 
THE UNIVERSITY OF NEBRASKA. 
