222 



CHARLES HARLAN ABBOTT 



TABLE 7 



Analysis of the reaction of Oniscxis F 2, exposed to light of 12.955 CM. for 100 

 successive stimuli. Duration of experiment one hour 



Some individuals appeared to 'tire out/ others continued active 

 as long as they were tested, but no correlation was observed 

 between delayed reaction and definiteness of turning from the 

 light. 



As an example of individual rather than of species behavior, a 

 summary is given in table 7, of the reaction of Oniscus F 2 which 

 responded to 100 successive stimuli. 



The characteristics of this animal were that it was very ac- 

 tive without any diminution of activity at the end of 100 stimuli 

 and that it was not as negative to light as are most individuals of 

 this species. In the first ten responses it was indifferent or posi- 

 tive, then it became much more negative for fifty successive re- 

 sponses, after which it became once more somewhat indifferent. 

 These changes are shown in the table by the column for the 

 angles of negativeness. As the animal was not negative at the 

 beginning, this table does not illustrate the usual behavior for 

 the species. 



From this series of experunents on repeated stimulation it 

 may be concluded that the phototaxis of Oniscus is not changed 

 or reversed by a long series of successive responses. Even when 

 the animals become gradually less active, they continue to turn 

 away from the light by as definite an angle as when they were 

 first exposed to it. 



