ANATOMY AND PHYSIOLOGY 



93 



In Orthoptera, the frequency of stridulation increases with the tem- 

 perature ; and the correlation between the two is so close that it is easy 



B 



FIG. 138. Stridulating organs of Microcentrum laurifoliunt. A, dorsal aspect of 

 file (s) when the tegmina are closed; B, ventral aspect of left tegmen to show file; C, dorsal 

 aspect of right tegmen to show scraper (s). 



to" compute the temperature from the number of calls per minute, by 

 means of formulae. The formula for a common cricket [probably a 

 tree-cricket, (Ecanthus niveus], as given by Professor Dolbear, is 



T = 50 + 1 ~ , which simplified is T = 40 H 



4 4 



Here T stands for temperature and N, the rate per minute. 



A similar formula for the katydid (Cyrtophyllus perspicillatus), 

 based upon observations made by R. Hayward, would be 



N- IQ 



Here, in computing N, either the "katy-did" or the "she-did" is taken 

 as a single call. 



