Animal Luminescence 585 



as well as biologists, in anything luminous. The animals were ob- 

 served one night in June at the border of a " ruiffeau " of the river 

 passing through Trans in Southern France. They saw little lumi- 

 nous bodies which they thought were glowworms and only on catch- 

 ing them did their true nature as crevettes appear. Although some 

 were completely luminous, others were not. In an attempt to ration- 

 alize these isolated cases of luminescence Thulis and Bernard re- 

 called that the glowworm is brighter at the time of mating and 

 that sea light is believed to be due to eggs and emanations of living 

 things. They wrote: " far from indicating a feeble state, the light 

 [of the crevettes] manifests that vigor necessary to fulfill sexual desire 

 [vceu de la nature], the more evident because nature has given them 

 a double organ to reproduce themselves." 



The first case of luminous marine amphipods appears to have been 

 observed by D. Viviani (1772-1840) . In his " Phosphorescentia 

 maris " (1805) , six species of Genoese crustaceans called Gammarus, 

 undoubtedly amphipods, are figured. Tilesius (1819) also lists 

 amphipods as luminous. However, the first indication that the light 

 of these forms, particularly the sand fleas or beach fleas of the genera 

 Orchestia and Talitrus, is bacterial in origin, comes from the obser- 

 vations of Alfred Giard (1889, 1890) and A. Giard and A. Billet 

 (1890) . These men isolated the luminous bacteria in pure culture 

 and thus introduced the idea of bacterial infection as a cause of 

 light, now recognized for a number of animal forms— marine, fresh- 

 water and terrestrial. 



SHRIMP 



The assessment of early records of luminescence among shrimp, 

 prawns, lobsters, and crabs is difficult, because in so many cases the 

 light undoubtedly came from luminous bacteria, as in the case of 

 Boyle's (1681) statement that " of all fishy substances the eggs of 

 lobsters which have been boiled shown the brightest." A similar 

 explanation must be given for the light of the river lobsters of Leo 

 Allatius (1586-1669) previously described, which looked like burn- 

 ing sulphur. They were discussed by the great student of Crustacea, 

 Philipp Jacob Sachs von Lewenhaimb (1627-1672), in his Gam- 

 marologia,^^ with the conclusion that the light would be more likely 

 to appear brighter in seacrabs than in river crabs. 



Crabs and lobsters are not known to be self-luminous. The first 

 observations of true shrimp luminescence is hard to place. These 

 animals, shrimp or prawns, may belong to either of three orders 



*' Sachs, Gammaroriim, vulgo cancrorum, Cap. XI, sec. 6, p. 212, Frankoforti et 

 Lipsiae, 1665. 



