UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 16, No. 21, pp. 393-400 March 3, 1917 



THE OCCURRENCE OF A RHYTHM IN THE 

 GEOTROPISM OF TWO SPECIES OF PLANK- 

 TON COPEPODS WHEN CERTAIN RECUR- 

 RING EXTERNAL CONDITIONS ARE ABSENT 



CALVIN O. ESTERLY 



UNIVERSITY OF CALIFORNIA PRESS 

 BERKELEY 



U' MAR i 3 1917 %] 



