222 Papers from the Department of Marine Biology. 



13. Luminous bacteria will live for over 24 hours in pure m/2 NaCl 

 or any sea-water salt mixtures containing both monovalent and divalent 

 cations. They will live for over an hour in m/2 KCl, but the Hght 

 disappears instantly in m/3 CaCl2 or m/3 MgCl2. 



14. Luminous bacteria will just live for slightly over an hour in 

 n/8,000 HCl, n/4,000 valerianic acid, and will live for over 24 hours 

 in n/1000 NaOH and n/500 methyl amine. The best light is given 

 on the alkaline side of neutrality, about the alkalinity of sea-water. 



15. The homologous aliphatic monohydric alcohols produce true 

 reversible inhibition or anesthesia of light-production. The concen- 

 trations which inhibit light-production in 10 minutes are: methyl 

 alcohol, 2 m; ethyl, m; propyl, 0.25 m; isobutyl, 0.08 m; amyl, 

 0.025 m; capryl or octyl, 0.002 m. 



16. KCN has verj^ little effect on light-production. The light is 

 only slightly affected in m/320 concentration in one hour. 



STUDIES ON A SQUID. WATASENIA SCINTILLANS. 



GENERAL CHARACTERISTICS OF LIGHT-PRODUCTION. 



The structure of the luminous organs and the habits of this form 

 have been well described by Ishikawa (si) and Sasaki (32) . The organs 

 are found on the tip of the ventral arms (3 in number), on the eyeball 

 (5 in number) , and over the ventral surface of the body (many) . Only 

 those of the arm-tips are brilliant enough to make chemical studies 

 feasible. Their light is a brilliant bluish white hke that of Cypridina. 

 The intensity is high, but is no doubt due in large part to the reflectors 

 present in the gland. The luminous material is burned within the 

 cells. The animal is a deep-sea form, coming to the surface near shore 

 to breed in certain bays of the Japanese coast, notably Toyama Bay. 

 The surface-water of this bay is brackish and the animals will not live 

 in it for even one hour. The deeper waters of the bay are more salty 

 and in these the squid will live for a longer time if the water is changed 

 to remove the poisonous ink. If oxygen be forced through fine pores 

 into the water, the squid, as Professor Shoji, of Kyoto University, has 

 shown, will live perhaps 8 hours, but this is the maximum. It will be 

 seen, therefore, that the animal is extremely delicate and it is not sur- 

 prising to find it of little value for chemical research. The arm-tip 

 light-organs respond only to stimulation and the response disappears 

 in 5 to 10 minutes after the animals are removed from sea-water. If 

 the arms are cut off and placed in sea-water the light-producing sub- 

 stance entirely disappears in 30 to 60 minutes, as we can determine 

 by grinding in a mortar. No light appears. The arm-tip light-organs 

 become exhausted very rapidly if continually stimulated, and the light 

 disappears very quickly after the organs have been ground in a mortar 

 with water or sea-water. 



