6 J. E. WODSEDALKk 



Then 10 specimens that had poor records in going toward 

 a stone against the light were taken and 21 daily experiments 

 were performed with each. The apparatus of the foregoing 

 experiments was used, except that the 16 candle-power incan- 

 descent lamp was again introduced at one end of the basin 

 and the specimens, in order to swim toward the stone, had to 

 go directly toward the light. The method of procedure was 

 practically the same as that of the previous investigations. 

 The results were surprising, for most of the specimens gradually 

 inhibited their normal negative phototaxis and proportionately 

 reinforced their positive reaction to the stone. However, the 

 individuals varied considerably. Some showed a slow but 

 steady progress for almost three weeks; some were quite docile 

 for a few days, but soon reached a limit; others learned very 

 little; still others would go toward the stone a fair distance 

 at the end of each set of 21 trials, but had to be started at 

 almost the same distance each day. The four different classes 

 of behavior are represented in table IV. 



TABLE IV 



Showing Four Different Cases of Learning, to Swim Toward Objects 

 Against the Rays of Light 



Day 



Specimen II 



First 

 Trip 



Last 

 Trip 



Specimen III 



First 

 Trip 



Last 

 Trip 



Specimen IV 



First 

 Trip 



Last 

 Trip 



1. 



2. 

 3. 

 4. 

 5. 

 6 

 7, 

 8 

 9 



to 



11 

 12 

 13 

 11 

 15 

 16 

 17 

 18 

 19 

 20 

 21 



1.5 in. 



2.5 " 



2.5 " 



3 " 



3.5 " 



3 " 



4 " 

 4 " 

 3.5 " 

 4 " 

 3.7 " 



4 " 

 4.5 " 



5 " 

 4.5 " 

 4. " 

 5.2 " 

 5.5 " 

 4 " 

 5.5 " 

 5.7 " 



4 



5.5 



6 



6 



6.5 



7 



7 



7.7 



8 



7.2 



8.2 



8 



8 



8 



8.5 



8.5 

 8 



1 



1 



1 



1.2 



1.5 



1.2 



1 



1 



1.5 



1.5 



2 



2 



2 



1.7 



1.7 



2 



2.5 



2.7 



1.7 



2 



2 



1.7 



2.5 



3 



3 



2.5 



3 



3.5 



2.5 



2.7 



2.5 



3 



2.7 



3.5 



3.2 



3 



3 



3.7 



3.5 



2.5 



3.5 



1 



1 



1 



1.2 



2 



1.5 



1 



1.2 



1.7 



2.5 



1.5 



1 



3.7 



2 



1 



3 



2.5 



1.7 



1 



2.5 



1.7 



4 



4.5 



5.5 



6.5 



7 

 7 



6.5 

 7.5 



8 



7.7 

 7 

 6.5 



8 



7.2 



6 



8.5 



7.7 



8 



7.7 



8.5 



7.5 



