268 S. O. MAST 



face, the source of light, toward the male. If the male is directly 

 above she twists the abdomen nearly through 180 degrees, if 

 to the right or left through 90 degrees, etc. Only when the male 

 is directly below does the female glow without first twisting the 

 abdomen. These responses occur, in the Western Maryland 

 species, almost invariably and they are so striking that they 

 cannot readily be overlooked. 



In thus directing the luminous surface of the abdomen toward 

 the male no matter where he is located, it is evident that the 

 character of the response must depend upon the location of the 

 stimulus. It is markedly different when the light produced by 

 the male strikes the anterior surface of the eyes than when it 

 strikes the posterior or any other surface. To put it anthro- 

 pomorphically, the female acts as though she recognized the 

 spacial position of the male. In these responses the female 

 does not begin to twist the abdomen until some little time 

 after the male glows. Her reaction takes place in the total 

 absence of the stimulating agent. After the flash of light which 

 induced the response has vanished she directs the ventral sur- 

 face of the abdomen toward the place where it was. It is there- 

 fore evident that the process of orientation in the female, (a 

 response resulting in a position of the abdomen bearing a specific 

 relation to the location of the male), is not regulated by the 

 continuous action of the stimulating agent as is demanded by 

 Loeb's theories of orientation (tropisms). The reaction is clearly 

 due to change in light intensity ; but it is without meaning unless 

 it is referred to what the changes which induce the response 

 represent, that is, the male and all subsequent occurrences in 

 the process of reproduction. 



In the male we find responses very much like those just 

 described. The female produces a flash of light in answer to 

 the glow of a male; then after a short interval, he turns, no 

 matter what his axial position may be, until he is directed 

 toward her and then proceeds. Thus if before the reaction he 

 chances to be directed from the female he turns through 180 

 degrees, if at right angles to her through 90 degrees, etc. If 

 the female is suddenly removed after she glows the response 

 of the male is precisely the same. He turns through the proper 

 angle and proceeds toward the spot where the female was when 

 she glowed. 



