222 LIGHT AND THE BEHAVIOR OF ORGANISMS 



the animals were trying fully to expose the intact eye and 

 still travel toward the light. Hadley (1908, p. 187) ob- 

 served somewhat similar reactions in positive lobster larvae 

 with one eye removed, as did also Miss Torelle (1903) in 

 frogs with one eye covered. Thus it will be seen that the 

 toads and frogs and lobster larvae tend to deflect toward 

 the blind eye, while butterflies, amphipods and flies tend 

 to deflect toward the functional eye. 



On June 27 several toads were exposed to light from one 

 glower, and from these the three which oriented most accu- 

 rately w^ere selected. The lens was then removed from one 

 eye in each toad. The following day they w^ere exposed 

 250 cm. from a 50 candle power Nernst glower in a beam of 

 light 45 cm. wide. The beam of course became narrower 

 as the source of light was approached. If set down so that 

 one side was illuminated all of these specimens turned 

 directly so as to face the source of light, but in all the head 

 was turned toward the blind side so that there was a distinct 

 curve in the spine, and after turning thus they hopped or 

 walked toward the glow^er, deflecting slightly toward the 

 injured side. They almost always reached the edge of the 

 beam of light before getting to its source and one passed 

 out into the shadow a few times. 



On July 14 the lens was removed from one of the eyes 

 of a large active toad which had oriented rather accurately. 

 The toad was then immediately exposed in the beam of 

 light. It hopped toward the glower apparently as accu- 

 rately as it did before the operation, but there w^as a tend- 

 ency to turn the intact eye toward the light whenever it 

 came to rest after each leap. The light intensity was much 

 reduced but still the specimen went directly toward the 

 glower. The following day this toad was again exposed; 

 it now went toward the source of light even more nearly 

 directly than on the preceding day. There was no longer 

 any appreciable tendency whatever to turn toward the 

 blind side. 



These results show that in this form and in all the other 



