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University of California Publications in Zoology [Vol. 19 



the table were obtained on the fourth day after the animals were 

 brought in, so that the table is not intended to show more than the 

 strong negative reaction of the copepods. The animals were released 

 in the center of the dish one by one, and in a few minutes the vessel 

 was turned through 180° and the distribution noted at short intervals. 

 The turning was repeated several times, and table 3 contains the 

 summary of the results. 



TABLE 2 

 The Changing Distribution op Six Specimens op Calanus in a Dish of Water 

 Standing Before the Window. The Animals were Brought in at 9:15 

 a.m. and were kept in the water that was in the collecting jar, at 

 Temperature of about 16°C. 



TABLE 3 



Distribution of Specimens of Calanus in a Dish 20 by 8 cm., Divided into Five 

 Equal Sections. The Dish was Turned at Intervals so that the Ends 

 Came Alternately Next the Window. Temperatures Above 17° C; Salinity 

 not over 34 o/ 00 . 



Number of observations 



Whole 



Number of r 



animals Negative 

 observed V 

 946 59 9 



per cent sho 



als in 



IV 



Total 



138 



positivi 

 5 



negative 

 % 

 95 



Center 

 of dis- 

 tribution 

 4. 



Since the intervals between observations were short some animals 

 were recorded as in sections nearer the window when, as a matter of 

 fact, they were really moving away from the light. Some, indeed, did 

 not move out of a given end section at all, whether it was next the 

 window or not. But on the whole the table shows the strong negative 

 phototropism of Calanus. 



