UNIVERSITY OF CALIFORNIA PUBLICATIONS 



ZOOLOGY 



Vol. 6, No. II, pp. 223-224 August 23, 1910 



CONTRIBUTIONS PROM THE LABORATORY 



OF THE 



MARINE BIOLOGICAL ASSOCIATION OF SAN DIEGO. 



XXXI. 



NOTE ON GEOTROPISM IN CORYMORPHA. 



BY 



HARRY BEAL TORREY. 



It was pointed out in a former 

 paper, 1 that although the larva of Cory- 

 morpha exhibits a marked negative 

 geotropism in locomotion, 2 attempts to 

 determine whether gravity in any 

 degree controlled the first locomotor 

 movements of the embryo — as indi- 

 cated, for instance, by the point at 

 which it left the eggcase — gave answers 

 in the negative. Recently the same 

 experiment has been repeated; and 

 though it has led to the same conclu- 

 sion with respect to the point of emerg- 

 ence of the embryo, observations were 

 made upon the development of the 

 frustules that show gravity to be a 

 factor controlling the direction of their 

 locomotion. 



Glass plates carrying several hun- 

 dred freshly laid eggs were fixed at 

 angles of about eighty-five degrees with 



1 I'niv. Calif. Pul.l. Zool., 3, p. 260, 1907. 

 - See also Jour. Exp. Zool., 1, p. 419, 1904. 



