62 



SAKYO KANDA. 



stimulation. Loeb's conclusion which was already referred to, 

 is thus confirmed. 



Preliminary Experiment B. According to Bohn and Mitsukuri, 

 Littorina littorea is negatively heliotropic. To test their results, 

 a simple method of "righting" experiments was adopted as fol- 

 lows: 



Ten selected individuals were placed dorsal side down on each 

 of two glass plates. The one was covered with the box, and at 

 the same time, the other was exposed to diffused daylight, both 

 for five minutes. The two lots were alternately covered and 

 exposed to daylight, after the animals had been refreshed in 

 sea-water and again turned "on their backs." The results 

 given in Table I. show that light considerably affects the "right- 

 ing" response of the animals. 



TABLE I. 



THE "RIGHTING" OF SNAILS ON A HORIZONTAL GLASS PLATE IN DARKNESS AND 

 DAYLIGHT FOR FIVE MINUTES (1912). 



In explanation of this "righting" reaction of the snails, it may 

 not be out of place to refer to Loeb's analysis in the starfish. 

 According to him, the "righting" of the starfish is a stereotropic 

 phenomenon, but not geotropic (10, pp. 64-65). Recently Moore 

 confirms this conclusion through experiments (13, p. 237), while 

 Jennings seems to have been misled in this respect (5, pp. 120- 

 148). The "righting" of the snails may also be a stereotropic 

 phenomenon, though it makes no difference for the present 

 purpose. In fact, however, as will be seen later, contact stimuli 

 interfere with the snails' reaction to gravity. The main point in 



