416 STELLA B. VINCENT 



The latches were the spoon dip, turn button, lift bar, slide bar, 

 peg-in-hole and bobbin and string. Some of the doors swung 

 inward and some outward. His program included (1) the learn- 

 ing of three boxes by each dog while still blind, (2) after learning, 

 a test for any disturbance following the darkening of the room; 

 (3) a test of rotation of the box ; (4) a retention test after 60 days ; 

 (5) the learning of three other problem boxes after the eyes had 

 been opened. As a matter of fact there was so little difference 

 between the results of the blind and the normal dogs that the 

 fifth part of the program was not undertaken. The test in the 

 darkness showed a slight disturbance in the blind animals, 

 indicating that the light evidently had some stimulating effect. 

 The disturbance was much greater in the normal dog. The 

 blind and normal dogs were equally affected by the change in 

 orientation. The retention tests for the two groups gave similar 

 results. To the reviewer it seems unfortunate that the last 

 part of the plan was abandoned. The mere fact that blind and 

 normal animals give the same results in time and accuracy in 

 a problem does not prove that the mode of procedure or the 

 sensory control is the same. It is not asserted to be so in this 

 case. But quite startling results often follow from the addition 

 of a stimulus as well as from its elimination and it is to be re- 

 gretted that when trained and operated animals were at hand 

 this step was not taken. 



Amphibians. The responses of young toads to intense and 

 moderately intense artificial light, to strong and weak diffuse 

 daylight, to sunlight and to colored light were studied by Riley 

 (47) in a long, careful series of experiments. He sums up his 

 work as follows: The young toads respond negatively to the 

 light from a projection lantern with an approximate illumination 

 of 10,000 ca.m. within the field of the experimentation." They 

 respond positively to incandescent light with an illumination of 

 approximately 44 ca.m., to strong and weak diffuse daylight 

 and to sunlight. "Except in the diffuse daylight the animals 

 jump toward the source of the illumination in a comparatively 

 straight line." "It is not improbable that both light intensity 

 and ray direction in the field are factors in these photic responses. 

 During orientation light intensity may play the more important 

 role, while the rays in the field may act as a guiding factor after 



