366 



WILLIAM H. COLE AND CARLETON F. DEAN 



tokinesis for this animal under an illumination of a 500 candle 

 power arc lamp is 30. 



The results of this trial not only agree with those of other 

 light adapted animals, but also vdih those from normal animal 

 15, trial 18, where one intensity was used, and also trial 34, 

 where three intensities were uspd. 



SUMMARY OF PHOTOKINETIC REACTIONS 



Because of their similarity all of the trials which gave photo- 

 kinetic reactions have been grouped together, and the averages 

 of photokinesis for the three kinds of animals calculated. This 

 was done by adding the per cents of photokinesis of all the 

 animals in each series and dividing by the number of animals. 

 These results are given in table 4. 



TABLE 4 



Normal 



Dark adapted 

 Light adapted 



PHOTO- 

 KINESIS 



per cent 

 22 



22.0 

 17 



2. Phototropism. Six large normal animals showed a distinct 

 tendency towards positive orientation to light; that is, they would 

 come to rest mth their heads close to the source of light, or with 

 their heads close against the jar move their tails swiftly back 

 and forth. It was observed that when the light fell on the tail 

 a few seconds, the animal would make two or three short move- 

 ments, not going out of the light but rather towards the source 

 of light. 



Animals 1 and 9 were the least marked as far as positive 

 orientation was concerned, the tendency being manifested in their 

 swimming about nearer the source of the light rather than away 

 from it. Hence their records were included with the photoki- 

 netic animals. 



Phototropism was especially marked in animals 13 and 14, 

 which were much larger and further developed than the others. 



