348 LUMINOUS ORGANISMS OF FAR EAST 



In April, 1953, I collected several pelagic species of luminous 

 Tomopteris with a plankton net in Aigae Bay, Hachijo Island. 



At the pearl cultivating station of Usa, Kochi Pref., I recently col- 

 lected luminous Tlielepus sp., the external appearance of which is 

 similar to that of Pohjcimis. These organisms live in the living shell 

 of pearl oysters and the tentacles become luminous when stimulated. 



Oligochaeta 



In Japan there appear two species of luminous earthworms. One is 

 terrestrial (Microscolex phosplwreus) and the other is a sea earth- 

 worm {Pondodrilus motsushimensis) . Microscolex phosplwreus is 

 worldwide in distribution. In Japan it was first found in 1934 at Oiso, 

 Kanagawa Pref., and later it was collected by many persons in every 

 part of Japan. This worm is small, 40 mm in length and 1-1.5 mm in 

 diameter, pale pink in color, and translucent. It is not luminous under 

 normal conditions but after strong stimulation it discharges luminous 

 mucus from mouth and anus. In November, 1939, Mr. Kuroki, a 

 teacher of the Fukuoka Middle School in Kushu, observed many 

 luminous earthworms crawling on the paved road near Fukuoka. On 

 that cold rainy night they were trod under foot by pedestrians aiid 

 crushed by bicycles and cars, and the soles of shoes, the tires of 

 bicycles and cars became brilliantly luminous. I also collected some 

 in my private garden at Zushi, Kanagawa Pref., in November, 1948. 

 As these species are small and are not luminous under normal con- 

 ditions, they are not known by most of the Japanese people. 



The sea earthworm is widely distributed along the coast of Japan. 

 The body, which is pale pink and translucent, is about 100 mm in 

 length and has 100 to 105 segments. The luminosity of this worm 

 was discovered by the late Dr. Kanda and myself when we saw them 

 in the wet sand at the tidal fine near Yokohama. This worm is also 

 not luminous under normal conditions, but it will discharge a yellow 

 luminous mucus from mouth and anus on strong stimulation or in- 

 jury. I have collected luminous sea earthworms at the tidal line of 

 tropical countries of Asia. According to Dr. Obuchi, these tropical 

 species are not the same as the Japanese species. 



I have also endeavored to cultivate luminous bacteria from the 

 luminous fluid of both species of worms and have obtained negative 



