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increased by several carbon compounds either free from or containing 
nitrogen, as glucose, levulose, glycerin, malates, asparagin, and 
many others that do not 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 specifie 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 unanalysable. 
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 aud oxidones. 
These units possessing the character of enzymes, and only 
oxidising special substances, or but few nearly related ones, we must 
accept that in this case, too, a preformation 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 experiments 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 glycerin too. 
In the photoplasm of Bacterium splendidum another factor occurs 
bj For Ph. phosphoreum, Aliment photogène, Archives Néerl. 1851. For Ph 
splendidum, Folia microb. 1915. 
