KEACTIONS OF A. TIGRINUM 271 



experiments. For the purposes in hand, the method was admir- 

 able, although it did require a great deal of patience and con- 

 siderable observation to make sure that the nose caps were tight. 

 It was with the idea of making a combination hoodwink and nose 

 cap that this method was appUed, but the irritation resulting 

 from the apphcation of the mixture of lampblack and collodion 

 to the eyes of the animal was too great to get normal reactions. 



Reactions to motionless objects. After securing a nose mask 

 which was satisfactory, the animals were placed in screened 

 aquaria in order that the observer might be concealed from view. 

 The reaction time was much increased. Twelve minutes, three 

 times as long as the average reaction time for the normal, was 

 allowed before a test was pronounced negative. The reactions 

 were recorded as negative when the animal made no effort to 

 obtain either bag and also showed none of the characteristic 

 motor activity of a stimulated animal, as positive when the 

 animal attempted to nose either bag. In the reactions so re- 

 corded, this reaction occurred within five to seven minutes 

 after the introduction of test materials into the aquaria. After 

 the attempt to nose, the animal paid no further attention to 

 either of the bags. 



The reactions obtained show distinctly that animals with the 

 sense of smell occluded cannot discriminate between test sub- 

 stances, for there was in no case any preference shown, the animals 

 nosing the sand bag, on the average, just as frequently as the 

 earthworm bag. The reaction is, to a large extent, one of con- 

 tact and is accidental. (Table 1, series 4 (a).) 



Reactions to moving objects. In contrast to the above reactions, 

 the reactions of the nose-stopped animals to moving objects is 

 quite rapid. The test sacks were moved about the aquarium 

 at various distances from the animal. All the reactions gave 

 an average reaction time of two and two-tenths minutes, the 

 animals showing no discriminaton between the test substances, 

 in marked contrast to the selective reaction obtained from ani- 

 mals with the possession of the normal respiratory mechanism. 

 (Table 1, series 4 (b).) 



