258 A.M.Banta 



1:40 2:10 2:40 3:10 3:40 4:10 4:40 5:10 



5.5 



4.5 



3.5. 



2.5 



1.5 



0.5 





Fig. 3. Asellus communis (21 individuals); Nov. 24, 1906; previous exposure, diffuse 

 daylight; illumination horizontal, 28i;5 C. IM. 



A graphic representation of the experiment recorded in Table 

 II is given in Fig. 3. The method ot representation is the same 

 as explained in connection with Fig. 2 (p. 254). 



Reference to Table II or Fig. 3 shows that in this experiment 

 Asellus after exposure to diffuse daylight was decidedly negative 

 to light of an intensity of 2855 CM. These animals had been in 

 the tank but 10 minutes when the experiment began, hence, the 

 thigmotactic influence was still quite effective. The mean aver- 

 age position at the start, 1:43 p.m., was 3:86; after five minutes 

 exposure, at 1 148, it was 2:95; after fifteen minutes, at 1 158, 2:64, 

 with a tendency to collect at the negative end alread)- beginning 

 to manifest itself. But the photo tactic response was still not the 

 most obvious one, for while at 2:07 p.m., (twenty-four minutes 

 after the experiment began) the mean average position was 1.95, 

 and 13 indivicuals were in Section i, four minutes later the mean 

 position was 3.55 and only 8 were in Section i, an equal number 



