266 S. O. MAST 



glass was held between male and female fire-flies so as to change 

 the color of the light flashed from one to the other. This change 

 produced no apparent effect on the mating responses of either. 

 The female answered the male as promptly and the male turned 

 toward the female as precisely as they did under normal con- 

 ditions. The same was found to be true when the ruby glass 

 plate was replaced by a flat flask filled with copper sulfate, or 

 with a cylindrical bottle filled with water, or with one, two, 

 three, or four thicknesses of paraffin tissue paper used in wrap- 

 ping baker's goods. 



These results seem to show that the recognition of the female 

 by the male may be independent of any possible difference in 

 the quality or in the intensity of the light produced by the 

 two sexes, or of any possible difference in the form of the lumi- 

 nous area. Moreover the fact that males respond to females 

 at various distances indicates that intensity cannot be of any 

 special importance in this, and the fact that males hidden from 

 females were often seen to turn toward glass jars or white paper 

 from which the light produced by the females w T as reflected 

 indicates the same with reference to form. We have left then 

 as possible distinguishing characteristics seized upon by the 

 male in the process in question, the time relation between the 

 glow of the male and the response of the female and possible 

 difference in the duration of the glow in the two sexes. 



(c) Thirteen males were put into one glass liter jar and three 

 females into another. These jars were then sealed and placed 

 25 cm. apart on a sheet of paper spread out in an open place in 

 the garden. Ten minutes later three free males had collected 

 about the jar containing the females and none around the other 

 jar, although the thirteen males produced many more flashes 

 of light than the three females. 



One of the free males was captured and so oriented on the 

 sheet of paper that he proceeded toward point very nearly 

 midway between the two jars. He was rather sluggish and 

 moved along slowly without glowing. When he reached a point 

 nearly between the jars one of the males in the jar glowed. 

 This did not appear to affect him in the least for he continued 

 on his course without any apparent change until a female in 

 the other jar answered the glow of the male, then he suddenly 

 turned almost at once directly toward the female and imme- 



