1919 J Esterly: Reactions of Various Plankton Animals 43 



eluded. All the tests were made in the light by the 50 by 40 cm. 

 window of the darkroom. 



TABLE 11 



The Phototropism of Eucalanus. Summary of Individual Kecords in all 



Intensities. Temperature 16°-20°C; Salinity 33 to 34 0/ 00 . 



Records of position 



Number Number 

 of of 



t of per cent of total showing Distal 



__ movement 



(cms ) 

 1,432 



It may be said that all the movements that show positive photo- 

 tropism are due to the drifting, and if these records were omitted 

 there would be only negative phototropism. But as the table stands 

 the responses are strongly on the negative side. 



GEOTROPISM 



The movements of Eucalanus in a column of water are of the two 

 general sorts. The animals "drift" up or down and also swoop in 

 either direction. 



Table 12 indicates the nature of the behavior in a vertical tube. 

 The table summarizes records that were made at intervals of varying 

 lengths, and the figures merely show the direction of movement without 

 regard to the method by which it is brought about. Records that 

 show no change of position are so few that they are omitted from 

 the table. 



TABLE 12 



The Geotropism of Eucalanus Under Different Conditions of Lighting and in 



Darkness. Summary of Individual Becords. Temperature 16°-20°C; 



Salinity 33 to 34 «/ 00 . 



Records of position 



Distance 



