Negative Phototaxis and other Properties of 

 Littorina as Factors in Determining its 

 Habitat. 



BY 



K. Milsukuri. 



Professor of Zoology, Imperial University. 



Daring my stay at the Marine Biological Station, Misaki in the 

 summer of 1900, I spent a part of my time in making some experiments 

 on Littorina, and the results embodied in the following pages are pub- 

 lished with the hopa that they may prove of some interest to those who 

 are engaged in similar studies. I wish to express my thanks to Mr. N. 

 Yatsu and Mr. T. Tsuchida for various assistance rendered during the 

 progress of the experiments. 



The species of Littorina that is commonest about the Station is 

 L. exigua Dunker. There is a second species also very abundant, L. 

 sitchana Phil, of which the var. brevicula is very conspicuous. Both 

 species live from the highest tide-level down for distances equal to a 

 vertical height of about two to three feet. They cease to be found long- 

 before the lowest tide-mark is reached which is perhaps four or five feet 

 still further down. The experiments recorded were made mostly on L. 

 exigua, as this is an easily diagnosed species and as it was desirable that 

 the experiments should be performed on one and the same species. I 

 shall not attempt to describe all the experiments performed but only such 

 as are important in bringing out the salient points. 



After the fact that Littorina shows a strong negative phototaxis wa9 

 established, I performed the following experiments : — 



Experiment 2 * — The following arrangements were fixed up. A 



* The number is that used in my note-book. 



