536 History of Luminescence 



tripos, and two other Cercariae, and a Vorticella (the rotifer, Syn- 

 chaeta baltica) which were always present and which he believed 

 to be the source of the light. However Michaelis could see no 

 " infusoria " on the surface of luminous fish. Pfaff, in an introduc- 

 tion to the Michaelis paper, pointed out that putrefaction, infusoria, 

 and luminescence went together and should be further studied. 



C. G. Ehrenberg (1795-1876), the foremost protozoologist of the 

 time, immediately became interested and asked Michaelis to send 

 to him in Berlin some sea water from Kiel. The water arrived after 

 a ten-day journey and only a small worm was found to be luminous, 

 described by Ehrenberg (1831) as Polynoe fulgurans. In a later 

 sample of sea water, sent from Kiel in 1832, Ehrenberg completely 

 confirmed Michaelis' observations and described such forms as Peri- 

 dinium tripos, fusus and furca and Prorocentrum micans, all of 

 which luminesced when acid was added to the sea water. In Ehren- 

 berg's great work (1834), a plate reproduced as figure 40 depicts 

 the above forms and in addition the new species, Peridinium michae- 

 lis and P. acuminatum. Peridinium tripos is the same as Cercaria 

 tripos Miiller,^^ a form whose present name is Ceratium tripos. A 

 second plate of Ehrenberg's (1834) paper depicts Nereis fulgurans 

 and Synchaeta baltica, the rotifer. Although Michaelis had described 

 this form, probably also seen by Baster (1757) , as a Vorticella and 

 said it was luminescent, Ehrenberg (1834: 536 and 538) never saw 

 it luminesce. He suggested that luminescence might be connected 

 with the breeding season, although some of his specimens carried 

 eggs and yet were non-luminous. In 1859 Ehrenberg again deter- 

 mined that the minute sparkling lights in the harbors of Naples and 

 Trieste came from dinoflagellates. 



Although the work of Michaelis and Ehrenberg was confirmed by 

 F. Dujardin,^2 E. Claparede and J. Lachmann (1858-1859) and P. 

 Gourret (1883) were unable to identify luminous dinoflagellates. 

 However, the positive results of F. von Stein (1883) , J. Reinke 

 (1898) , and many others indicate that these organisms give rise to 

 the great displays of light, which evoked the enthusiastic descriptions 

 quoted at the beginning of this chapter. 



An interesting parallel can be drawn between discovery of the 

 biological origin of diffuse sea light and that of wood and flesh, as 

 recorded in Chapter XV. The dates of MacCulloch's (1821) , Pfaff 's 

 (1823, 1828), Michaelis' (1830), and Ehrenberg's (1832, 1834) 

 studies on flagellates may be compared with the date of Derschau, 

 Nees von Esenbech, Bishof and Noggerath (1823) on luminous 



" Miiller, O. F., Zoologiae danicae prodromus, Hauniae, 1777. 

 "According to Moliscii (1904: 16). 



