1278 
similarity exists everywhere, *) notwithstanding the enormous diffe- 
rences in the respective phosphorescent organs. 
Another consideration which induced me to study with particular 
care the production of light by living microbes was the following. 
I saw the great difficulty of explaining by the enzyme theory a 
function so obviously the attribute of the living protoplasm. Yet I 
had the conviction that if it were possible to account for this excep- 
tional character by that theory, the same would be the case for 
any other character, physiological or morphological. Presently we 
shall see that the facts are in accordance with the expectation. 
Not all luminous bacteria are equally well qualified for this in- 
vestigation. Photobacter splendidum, common in the North Sea at 
the end of summer,*) and Ph. phosphoreum Coun, always present 
on sea-fish, whose properties are very different and in many respects 
complementary, are recommendable. Ph. splendidum produces trypsin, 
urease, diastase and invertase, and assimilates mannite with light 
production. Ph. phosphoreum has none of these enzymes and does 
not attack mannite. *) 
The chief result of this study is that the function of phosphore- 
scence may be ‘ascribed as well to living protoplasm as to one or 
more enzymes. 
I chose this function to elucidate the theory with regard to a 
physiological character; the production of the cell-wall shall be 
treated to test it from a morphological point of view, and also in 
the latter case it can be shown that the protoplasm as well as one 
or more enzymes may be regarded with the same right as the 
cause of its formation. 
The subsequent considerations must be given in a short and 
somewhat aphoristie but | think not unclear form. 
Enzymes considered as the bearers of phosphorescence. Irritability. 
Already in 1898 Rarait. Dusois endeavoured to demonstrate that 
phosphorescence should be considered as caused by an enzyme-action. *) 
') Perhaps with exception of the higher Fungi, where the luminosity seems to 
be in correlation with a state of collabescence. 
*) Die Leuchtbakterien der Nordsee im August und September. Folia microbio- 
logica, Bd. 4, Pag. 1, 1915. 
5) Aliment photogène et aliment plastique des bactéries lumineuses. Archives 
Néerlandaises T. 24, P. 369, 1891 (Feeding of Ph. phosphoreum Coun.) 
4) R. Dusots, Lecons de Physiologie générale, Pag 450 and 524. Paris 1898, 
Drawings of the phosphorescing organ of Pholas by Uric DAHLGREN : The pro- 
duction of light by animals. Franklin Institute, February 1916, Pag 38, 
: 
