54 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA 



was present in sufficient quantity to account for the amount of light produced 

 at one time. On the contrary, it must have been the combined result of all the 

 groups, since many genera and species of dinoflagellates were abundant, often 

 to the exclusion of other known, light-producing organisms. 



The probable seat of luminosity has yet to be determined. In Xoctiluca 

 it is found as spots of light on the surface, which may be localized or may include 

 the entire periphery of the organism. The presence of oil globules or allied 

 substances is common throughout the dinoflagellates, especially near the surface, 

 and it is probable that the material from which luciferine is secreted is drawn 

 from these bodies. No observations have yet been made, however, upon the 

 condition of these before and after the exhibition of light. 



