253 



corresponding to the ends of the threads, closely grouped near the flagellum, but 

 farther on the surface at greater relative distances 1 ). The sudden radiance of 

 Noctiluca by shaking the sea-water wherein it is suspended is well-known. When 

 fatigued the cells become entirely luminous and de Quatrefages called the 

 so produced light pathological light, but he does not say whether it originates from 

 the cell-wall or the cavity. 



A principal argument for the view that the photoplasm of the luminous bacteria 

 possesses the properties of the protoplasm lies in the relation between food and 

 luminosity. For if peptones are present in sufficient quantity the phosphorescence is 

 considerably increased by several carbon compounds either free from or containing 

 nitrogen, as glucose, levulose, glycerin, malates, asparagin, and many others that do 

 riot act as stimuli, but as in the normal respiratory process are oxidised to carbonic 

 acid and water. Peptones alone can also be broken off by the photoplasm, likewise 

 under production of ammonium carbonate, carbonic acid, and water. Phosphorescence 

 thus proves to be bound to the photoplasm in the same way as the respiratory process 

 in general is bound to the protoplasm, so that it may be said that the photoplasm of 

 the luminous bacteria forms part of their respiration protoplasm. 



As now the chief criterion of enzyme action consists in the fact that enzymes act 

 only on a specific substrate, in the case of phosphorescence this criterion at first sight 

 seems to fail, and the process more reminds of a catabolism bound to the protoplasm 

 as a whole and which is rather unanalyse. 



But considering what should be understood by a catabolism we find in many cases 

 that it is based on the co-operation of various factors of the nature of enzymes. The 

 respiratory process itself supports this view, for recent enzymological investigations 

 have shown that the respiration protoplasm is composed of different factors, in 

 general called oxidases, with the specific distinction of peroxidases, oxigenases and 

 oxidones. 



These units possessing the character of enzymes, and only oxidising special sub- 

 stances, or but few nearly related ones, we must accept that in this case, too, a pre- 

 formation of enzyme-substrates or enzymoteels takes place on which they exert their 

 function. The composition of the photoplasm of several of such factors or oxidases 

 is thereby rendered probable, and the ease wherewith by means of mutation experi- 

 ments with the luminous microbes hereditary constant races arise of very unequal 

 phosphorescence (but as it seems always of the same colour), is evidently connected 

 with these facts. 



That the factors of the photoplasm of the various species of luminous bacteria are 

 not always the same follows from the before described experiments about the relation 

 between nutrition and phosphorescence -}. 



So, in the photoplasm of Bacterium phosphoreum an oxidase must exist associated 

 with a substrate resulting from peptones only, and another oxidase whose substrate is 

 an unknown matter, produced by peptone and sugars and perhaps by peptone and 



') Memoire sur la phosphorescence de quelques invertebres marins. Ann. d. sc. nat. 

 Zoologie, 3nie Ser. T. 14, pag. 326, 1850. Vide also R. Dubois. Lecons de Physiologic 

 generate, pag. 498, Paris 1898. 



-) For Ph. phosphoreum. Aliment photogene, Archives Neerl. 1851. For Ph. plendidmn 

 Folia microb. 1915. 



