1 62 S. STILLMAN BERRY. 



In a popular volume by C. F. Holder ('87, p. 46), descriptive 

 of luminous organisms in general, but unfortunately none too 

 carefully compiled, occurs the following paragraph on the 

 Cephalopoda: 



'The highest forms of the Mollusca, the Cephalopods, cuttle- 

 fishes, are probably at times luminous. I have noticed what I 

 presumed was a delicate, sensitive glow about an Octopus in a 

 semi-darkened tank, but I am not satisfied to make the state- 

 ment as a fact. These forms are so remarkable for the waves of 

 color that pass over them, and which seem to make them trans- 

 parent, that one could readily be deceived. 



'The little Cranchia (Plate IV., Fig. 2) is a light-giver, its 

 phosphorescence having been distinctly observed. It is an 

 ally of the giant squids, which have been found fifty-five feet in 

 length, and which, if luminous like their pygmy relative, would 

 present a marvelous spectacle, darting veritable living arrows 

 through the depths of the sea. 



"Giglioli refers to the phosphorescence of Loligo sagittatus, 

 and to that of several small Octopods observed by him at Callao 

 and Valparaiso. Their bodies gave out a pale whitish light, 

 uniformly distributed." 



It happens that Cranchia is a genus which is now known to 

 possess definite photogenic organs, but these have been found to 

 occur only on the eyeball, whereas the rather poor figure given 

 by Holder represents the animal as brightly and evenly glowing 

 over the entire surface, body, head, arms, tentacles, and all. 

 As to the supposed photogenic properties of Polypus and related 

 octopods, both Darwin and Giglioli would seem to have been 

 too accurate observers for the explanation advanced by Holder 

 to be entirely satisfactory. 



Chun, in his narrative of the cruise of the "Valdivia" (:O3, 

 pp. 569-570; also :03a, p. 81 ; :io, p. 50) gives up to this time the 

 fullest account of the actual display of photogenic propensity by 

 a cephalopod we have been able to find, and he followed this in 

 later publications by a very considerable contribution to our 

 morphological knowledge of the organs responsible for the 

 manifestation. The specimen observed proved to belong to a 

 wonderful undescribed species, the Lycoteutliis diadema (Chun). 



