346 LUMINOUS ORGANISMS OF FAR EAST 



coast. The following summer observations were continued oflE the 

 coast of Otaru, Hokkaido. 



My first experience was in December, 1952, in the sea off Ito, Izu 

 Peninsula, and the second was in August, 1953, in the sea off Otaru, 

 Hokkaido. In both descents, conducted at night, I saw the lumines- 

 cence of Beroe and Cestum under natural conditions and at a depth 

 of about 20 to 50 meters. I can never forget the beautiful luminous 

 appearance of the transparent, long, bandlike Cestum through the 

 window glass of the chamber, as the animal emitted a very beautiful 

 flash of light. At the same time I saw numberless luminous Copepoda 

 running across the window like a snowstorm. 



Below the surface, suspended materials like snowflakes could be 

 seen with the naked eye, wherever the beam of the projector light 

 fell. According to the laboratory experiments of Drs, Suzuki and 

 Kato of Hokkaido University, these suspended flakes are assumed to 

 be aggregates of distintegrating bodies of plankton organisms. These 

 unidentified masses have been named "Marine snow" or "Sea snow" 

 or "Plankton snow." One night in the summer of 1953, in the sea off 

 Otaru, Hokkaido, I observed that some of these suspended flakes were 

 luminous like the ctenophore Beroe. They were suspended in the 

 water and, coming gradually to the window glass, they were crushed 

 to minute luminous spots and then faded out. My own opinion is 

 that luminous bacteria grow on the suspended flakes, causing them 

 to be luminous. 



Pyrosoma and Salpa 



There is one report on a possible luminosity of Salpa in Japan. 

 According to Tokioka (1937) CtjcJosalpa pin7mta var. polae (Sigl), 

 18 to 22 mm in length, appearing at Seto, Wakayama Pref., has one 

 luminous stripe, but he never saw hght from these individuals in the 

 dark. Pyrosoma and Salpa are common in Japanese waters. About the 

 middle of April, great numbers occur in the waters of Hachijo Island. 



These Pyrosomae have been identified as Pyrosoma atlanticum 

 Peron and two species of Salpa as Thetys vagina (Tilesius) and 

 Pegea confoederata (Forskal) by Dr. T. Tokioka. Another small spe- 

 cies of Pyrosoma, which was caught in a trawl net in Suruga Bay 

 was identified as Pyrosoma verticillatum Neuman. 



