STUDIES ON BIOLUMINESCENCE. 

 XIII. LUMINESCENCE IN THE CCELENTERATES. 



E. NEWTON HARVEY, 

 PRINCETON UNIVERSITY. 



INTRODUCTION. 



During a recent trip to the Pacific coast, the opportunity 

 presented itself of studying light production in a number of 

 ccelenterates and of making observations on other luminous 

 forms. These studies were carried out at the Puget Sound 

 Marine Station, Friday Harbor, Washington, and the author 

 expresses his keen appreciation of the facilities afforded him 

 there by Professor T. C. Frye, director of the laboratory. 



We are indebted to Panceri (i) for most of our knowledge of 

 luminescence among the ccelenterates. The present paper sup- 

 plements his work and gives the facts in the case of certain 

 forms found in Puget Sound. 



EXPERIMENTS ON HYDROMEDUS^. 



Seven species of hydromedusan jelly-fish were obtained at 

 Friday Harbor, namely, ^Eguorea forskalea, Mitrocoma cellularia. 

 Phialidium gregarium, Stomatoca atra, Sarsia rosaria, Melicerta 

 sp. ? and an unidentified form. One scyphomedusan, Cyancea 

 sp. ?, is also occasionally to be collected. Of these only the 

 first four produce light and only the first three are markedly 

 luminous. The first five were very common forms, especially 

 ^qiiorea, Mitrocoma and Phialidium, obtained in the morning 

 from the laboratory float where they live in water of rather low 

 temperature. Their appearance is somewhat capricious, how- 

 ever, and on several days only one or two were seen. 



^Lquorea and Mitrocoma, if to 3 inches in diameter, and 

 Phialidium, about I in. in diameter, produced light of a bright 

 bluish-green color (but not so blue as the ostracod, Cypridina} 



from spots along the edge of the umbrella at the base of the 



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