300 SUMMARY OF CUP.RENT RESEARCHES RELATING TO 



Commensal Ostracod.* — P. Paris describes Sphferoniicola topsenti 

 g. et sp. n., a remarkable commensal Ostracod found attached tocaverni- 

 colous Isopods — namely, Csecosphaeroma virei Dollfus from the Jura, and 

 C. himjundum Dollfus from Burgundy. The creature lives on the under 

 surface of the Isopod at the base of the appendages, especially of those in 

 front. There are usually several living together. The relatively large 

 white ova (125 fx in longest diameter) are fixed singly by cement to the 

 Isopod and do not exceed three or four in number. The animal has a 

 shining surface and a pure white colour, transparent in the appendages. 

 There is no trace of eyes. The external genital organs are strongly 

 developed. The female was about 415/x in length, the male about 440/i.. 



Luminescence of Japanese Species of Cypridina.j — E. Newton 

 Harvey has studied the Japanese Ostracod Cypridina hilgendorfi Miiller 

 in relation to its luminescence. The luminous secretion comes froiB 

 several spindle-shaped yellow cells on the upper lip, and is exuded ii;itO' 

 the sea as perfectly clear granule-free non-fluorescent material. The 

 light is homogeneous and bluish-white in colour. If the luminous 

 secretion stands, the light disappears ; if there be added an extract of 

 Cypridina heated to boiling, the light returns. Thus this Ostracod 

 gives a luciferin-luciferase reaction similar to that given by Pholas 

 dactylus as described by Dubois. Contrary to Dubois, the author finds 

 that the luciferase is the source of the light, and not an enzyme causing 

 light-production by oxidation of luciferin, for light can be obtained 

 from luciferase by substances incapable of oxidation, such as salt, chloro- 

 form, and ether. The new names of photogenin or light-producer 

 for luciferase, and photophelein or light-assistor for luciferin are 

 proposed. 



Oxygen is necessary for light-production. Both photogenin and 

 photophelein will easily pass through a Pasteur-Chamberlain or Berke- 

 feld filter. Photophelein dialyses readily through heavy parchment or 

 collodion, photogenin with great difficulty or not at all. The light- 

 producing substances may be dried and thoroughly extracted with ether 

 without impairing their light-giving power. Photophelein occurs 

 throughout the body of Cypridina, photogenin only in the luminous 

 organ. While photogenin will give light with many substances, photo- 

 phelein will give light only with the photogenin of the luminous organs. 

 Many other facts are demonstrated. In the natural secretion of Cypri- 

 dina, or in the whole animal, there is always enough photogenin to 

 completely use up the photophelein. The photogenin from one animal 

 will use up a large additional amount (at least 100 times the concentra- 

 tion in one animal) of photophelein, but not an indefinite amount, so 

 that photogenin is not a true enzyme in the strict sense of the word, 

 unless it be an enzyme poisoned by its own reaction products. The 

 photogenin-pbotophelein system resembles the zymase-co-zymase system 

 to a remarkable degree, but it is best for the present to regard photo- 

 genin not as an enzyme, but merely as a substance auto-oxidisable only 

 in presence of photophelein. 



* Comptes Eendus, clxiii. (1916) pp. 307-9. 



t Amer. Journ. Physiol., xlii. (1917) pp. 318-41. 



