REACTIONS OF A. TIGRINUM 



273 



side. The arrangement proved very useful in the differentiation 

 of sight stimukis from that of smell and was used on all of the 

 four series of animals. Two kinds of substances were used, dif- 

 fusible and non-diffusible but visible. For the first, an infusion 

 was made of minced earthworm, generally allowed to stand over 

 night and filtered in the morning. The resulting extract con- 

 tained no visible solid substance, but simply the juices and body 

 fluids of the earthworms. This proved to be a very potent sort 



. TABLE 1 

 Reactions to test sacks 



Normal \ 2 



Nose-stopped 4 



Blinded 5 



Nose-stopped and 6 / 

 blinded \ 



NUM- 

 BER OF 

 TRIALS 



10 

 10 



10 

 10 



10 

 10 



10 

 10 



10 

 10 



10 

 10 



Aquarium 



Terrarium 



Dark room 

 In aquarium 



Aquarium 



Aquarium 

 Aquarium 



Aquarium 

 Aquarium 



CONDITION OP TEST 

 SUBSTANCE 



a)Motionless 

 b)Moving 



a)Motionless 

 b)Moving 



a)Motionless 

 b)Moving 



a)Motionless 

 b)Moving 



a) Motionless 



b) Moving 



a)Motionless 

 b)Moving 



REACTION 



Positive 

 Positive 



Positive 

 Positive 



Positive 

 Positive 



Attracted 

 equally- 

 Positive 

 Positive 



Negative 

 Negative 



minutes 



3.8 



15 



Over 30 



12 



4.2 



of stimulus. It was appUed by means of a pipette along the 

 wall of the aquarium, and diffusing through the water passed 

 under the partition. The observer was screened from view. 

 The reactions were remarkably quick and vigorous, in many 

 cases the animal moved to the central portion of the partition 

 and snapped at the diffusing substances which it perceived but 

 certainly did not see. 



The non-diffusing substances used were bits of rubber tubing 

 and uncut earthworms. According to the work of Olmsted ('18), 



