170 APPENDIX. 



2. PAGE 9. Kiel observed this phenomenon in Peridinium. The 

 following species of luminous forms existing in the Baltic Sea have been 

 described by Ehrenberg : Prorocentrum micans, Peridinium michcelis, Peri- 

 dinium micans, Peridinum fuscus, Peridinium f urea, Peridinium acuminatum, 

 Lynchata ballica, and a species of Stentor. 



3. PAGE 9. Giglioli and his assistant, De Fillipi, observed luminos- 

 ity in the gelatinous mass described by Haekel as Citophora. 



The genera of those low forms most remarkable for luminosity are 

 Thalassicolla, Collozoum, Sphcerozoum, and Collosphcera. Giglioli states 

 that the forms of this group which are found in the Indian Ocean and 

 China seas are not luminous. 



4. PAGE 11. Dymophora fulgurans. 



5. PAGE 12. Other light-givers of this group are Willsea prolifera, 

 Bourganivillia, and Lizzia. 



6. PAGE 12. Mueniopsis leidyii. 



7. PAGE 13. The Lucernaria is a very rare form of medusa on oui 

 northern shores, and particularly characteristic in color and form. It 

 is more like a polyp in texture, and its rich beryl color distinguishes it 

 from all other forms. It is related to the Discophores, animals belong- 

 ing to one of the groups of jelly-fishes, or medusa. 



8. PAGE 14. Schafer has observed radiating fibres on the under side, 

 but there is no evidence to show that the luminosity originates here. In 

 fact, the outer surface, where the cells of the delicate epithelium, or skin, 

 contain minute points of fatty material, is equally phosphorescent. The 

 tentacles become luminous, and it is supposed that they contain no nerves 

 except at the margin of the disk. In some instances the light seems well 

 defined at the so-called eye-spots at the edge of the disk, but its sudden 

 fluctuations render any attempt at locating a photogenic structure difficult. 



While numerous theories are advanced, investigators are entirely at 

 fault as regards any satisfactory explanation of the phenomenon. Therf. 

 are certain conditions which are not favorable to the emission of light; 

 and observers have seen medusce vividly luminous at one time, and not so 

 at another. 



It has been suggested that the light is subject to the so-called will of 

 the creature. A better theory, perhaps, would attribute the luminosity 

 to certain peculiar conditions, or to certain stages of existence. 



