Vol. XXVI. January, 1914. No. i 



BIOLOGICAL BULLETIN 



ON THE GEOTROPISM OF PAR AM EC I UM AND 



SPIROSTOMUM. 1 



SAKYO KANDA, 



DEPARTiMENT OF PHYSIOLOGY, UNIVERSITY OF MINNESOTA. 



I. Introduction I 



II. The Mechanical Theory 2 



1. Experiments on Paramecium caudatnm 7 



2. Experiments on Paramecium teres 12 



III. The Pressure Theory and Its Criticism 13 



IV. The Resistance Theory 14 



1. Experiments on Paramecium caudatnm i9 



2. Experiments on Spirostomum teres 19 



V. The Statocyst Theory and Its Criticism 20 



VI. Conclusions 21 



VII. Summary 22 



VIII. Bibliography 23 



I. INTRODUCTION. 



Through the kindness of Professor Ralph S. Lillie, I was given 

 an opportunity to study in the physiological department of the 

 Marine Biological Laboratory at Woods Hole, Mass., during the 

 summer July i-September 4 -of 1912. During my stay the 

 following experiments were made under the direction of the 

 instructors in the physiology course, especially of Professor 

 E. P. Lyon. I wish here to acknowledge my indebtedness to 

 Professors Garrey, Knowlton, Lillie, Lyon and Meigs. 



The general phenomena of geotropism in the protozoa are well 

 known through the work of Schwarz (22), Aderhold (i), Massart 

 (18), Jensen (11-12), Sosnowski (23), Moore (19), Jennings 

 (5-10), Lyon (16-17), Harper (3-4), and others. The descrip- 

 tion of the phenomena given in these papers is exhaustive and 

 no recapitulation is needed. 



In this paper an attempt has been made to subject to a critical 



1 From the Marine Biological Laboratory, Woods Hole, Mass. 



