264 



BRADLEY M. PATTEN 



In a group of four animals, the left median eyes of two indi- 

 viduals, and the right median eyes of the remaining two indi- 

 viduals, were covered with an opaque cap sealed on with 

 asphaltum varnish. These animals were then subjected to 

 equal bilateral stimulation between opposed lights each deliver- 

 ing an intensity of 120 candle meters. The reaction measure- 



TABLE 5 



Reactions of Mastigoproctus with one median eye covered, to equal bilateral illu- 

 mination. The opposed beams were each of 120 candle meters intensity. Com- 

 pare these measurements with the normal reactions (table 4) to the same conditions 

 of illumination 



ments given in table 5 show that this procedure caused a 

 consistent deflection toward the side of the blackened eye. 

 • Similar experiments in which the lateral eye groups were 

 covered on one side of the head, caused an equally consistent 

 and somewhat more extensive unbalancing of the normal reac- 

 tion (table 6). In forty tests there appeared only one deflection 

 (and that a very small one) toward the normal side. In all 

 other cases the deflections were toward the side on which the 

 eyes had been covered. A comparison of the measurements 

 given in tables 5 and 6 with the measurements obtained from 



