524 History of Luminescence 



man zoologist, Ernst Haeckel (1834-1920) , included the animal in 

 a special order of the Flagellates, the Cystoflagellata.-^ Thus ends 

 the story of the discovery of a famous organism. Nineteenth-century 

 studies on the physiology of Noctiluca will be found in the section 

 on Flagellata in chapter XVI. 



Eighteenth-Century Theories of Sea Light 



Although phosphorescence of the sea came definitely to be con- 

 nected with minute organisms in the 1750's, certain physical and 

 chemical explanations of the light still persisted, outgrowths of the 

 earliest views of the seventeenth century. These physical or chemi- 

 cal theories may be divided into at least six groups: (1) Electrical; 

 (2) Mechanical; (3) Insolation; (4) Phosphorus; (5) Putrefaction; 

 or (6) a combination of the above. 



ELECTRICAL 



Electrical theories were very popular in the eighteenth century. 

 Jacques Charles Francois de la Perriere de Roiffe (died 1776) sup- 

 ported the electrical view in his Mechanism e de I'Electricite (1: 

 111, 1756) , but without making personal investigations. Guillaume 

 Hyazinthe Joseph Jean Baptiste Le Gentil de la Galaisiere (1725- 

 1792) , the astronomer at Paris, made a journey to the Indies in 

 1760 to observe the transit of Venus. From observations on this 

 trip, he (1761) was inclined to consider sea light electric in origin, 

 although he did say that not all of it was due to electricity. He 

 mentioned reflection and the fact that dwellers by the sea regard 

 the light phenomena as due to fish spawn. 



M. Bajon (died 1790) , a physician at Cayenne in French Guiana 

 and correspondent of the French Academy, also considered (1778) 

 electricity, resulting from collision of currents, to be the source of 

 light. He claimed to obtain more luminescence when the sea was 

 disturbed with a metal object than with a glass one. 



He also noted that with continued agitation of the sea water, the 

 light became weaker, and if placed in a well-stoppered bottle, the 

 light disappeared, but would return if the sea water were poured 

 into a pail and exposed to the air. His final conclusion attributed 

 the light to " une materie phosphorique qui a une analogic directe 

 avec I'Electricite." 



"^According to C. A. Kofoid and O. Swezy {Mem. Univ. of Califorrtia, 5, 1921), 

 who removed Noctiluca from Haeckel's order of cystoflagellates, by the rules of zoologi- 

 cal nomenclature, the correct name should be Noctiluca scintillans Macartney. There 

 appears to be only one species, although various specific names have been applied. See 

 this monograph for synonymy. 



