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portant finding. This was that certain compounds (sugars and poly- 

 alcohols) had the property of almost instantaneously increasing the 

 luminosity of plates which by "staling" had more or less completely 

 lost the property of phosphorescing. This made him conclude that one 

 had to discriminate between photogenous and "plastic" (i.e., growth 

 promoting) food substances of luminous bacteria. This observation 

 would certainly be interpreted to-day as a strong indication that light 

 production is intimately connected with the respiration processes of 

 the cells, and is independent of proliferation. BEIJERINCK himself ar- 

 rived at a different conclusion concerning the metabolic process res- 

 ponsible for the light production; this, however, does not detract 

 from the value of these fundamentally important observations. 



Mention should be made also of the fact that BEIJERINCK devised 

 several elegant applications of the principles outlined above for the 

 detection of various enzymes. For instance the first experimental 

 proof for the existence of the enzyme lactase (in Saccharomyces Kefyr) 

 was adduced from application of these methods. WIJSMAN l ), working 

 under BEIJERINCK'S direction, applied the method successfully in 

 analysing the amyloclastic enzymes present in barley ; his findings did 

 not attract much attention at the time, but have since been corro- 

 borated by recent investigators 2 ). 



Ten years later BEIJERINCK published his now well-known ob- 

 servations on the applicability of luminous bacteria for the detection 

 of the traces of oxygen formed in the photochemical reduction of 

 carbon dioxide in green cells 3 ). The experiments culminate in the 

 observation that with the aid of this method it is even possible to 

 prove that production of oxygen occurs, when a suspension of chloro- 

 plasts, obtained by crushing green leaves and filtering the diluted 

 mass, is illuminated. In a fairly recent survey on photosynthesis it is 

 still remarked that this experiment seems to offer the only example in 

 which it has been possible to prove the occurrence of an - albeit 

 weak photosynthetical action in the absence of intact living 

 cells 4 ). It has, however, to be added that recent investigations seem 

 to prove that this oxygen evolution is not the result of carbon di- 

 oxide assimilation, but depends on a photochemical decomposition of 

 some peroxide active in the photosynthetic apparatus 5 ). 



In the last phase of his career BEIJERINCK returned once more to the 

 subject in question in a paper describing Photobacterium splendid-urn, a 

 still unknown species, responsible for the phosphorescence of the 



') H. P. WIJSMAN, De diastase beschouwd als mengsel van maltase en dextrinase. 

 Amsterdam, 1889. 



2 ) Cf. G. A. van Klinkenberg, Ergebn. der Enzymforschung 3, 73, 1934. 



3) Proc. Kon. Akad. v. Wet. Amsterdam 4, 45, 1901. 



4 ) R. EMERSON, Ergebn. d. Enzymforschung 5, 305, 1936. 



5 ) H. KAUTSKY, Die Naturwissenschaften 26, 14, 1938. 



M. W. Beijerinck, His life and his work. 8 



