JOUKNAL OF THE COLLEGE OF SCIENCE, TOKYO IMPERIAL UNIVEESITY. 

 VOL. XL, ARTICLE 3. 



Notes on the Physiology of 



Charyhdea rastonii. 



Br 

 Naohide YATSU, Rigdhuhahusi. 



With 5 Text-figures. 



Late in the summer the httle inlet in front of the JVIisaki Biologi- 

 cal Station abounds with hundreds of the interesting cubomedu- 

 sa, Charyhclea rastonii. They are often so numerous that they 

 cause not a little annoyance to the bather. To the student of 

 cœlenterates, however, the circumstance affords excellent opportunity 

 for investigation. - 



Although the morphology of cilbomedusae has been studied to 

 such an extent that farther investigation seems scarcely necessary, 

 yet our knowledge of their physiology is very poor, the only works 

 on this subject being the two papers by Conant (''98) and by Berger 

 ('00), and no doubt much is to be done in future along that line. 

 It was in the summer of 1915, .Vugust 28-Öeptember 2, that I per- 

 formed at Misaki a few simple experiments upon Charyhclea rastonii. 

 In August of 1916 some of these were repeated with the same 

 results. In the following pages I shall l)riefly describe the results 

 of my experiments and observations on this interesting medusa. 



I. Light reaction. 



Charyhclea rastonii behaves in response to photic stimulus quite 

 differently from C. xaymacana observed by Conant. The Jamaican 



