230 McKenney On Luminous Bacteria. 



is modified muscular or contractile tissue. In any case there is analogy 

 between the bacterial contractile flagellse and contractile animal muscle. 

 Today physicists are pointing out the close connection between light and 

 electricity. The large. NaCl content in the electric (or modified con 

 tractile) organ of the torpedo on the one hand and the large sodium need 

 of the photobacteria taken with the relations between light and motion 

 on the other hand are full of significance. 



With the facts at hand one may reasonably- draw a few conclusions 

 concerning the nature of light production. The fact that no luminous 

 substance has ever been certainly isolated rather inclines one to disbe 

 lieve the extracellular theory. The fact that the temperature limits for 

 life are without the limits for luminescence points to the intracellular 

 theory. The fact that a slight amount of ether may cause a cessation of 

 light emission and yet not stop growth points in the same direction. 



While these facts lead us to strongly believe that luminescence is an 

 internal (oxidation) process, yet there are not facts enough at hand to 

 warrant the assumption that this process is inseparable from life and 

 incapable of exact reproduction in the laboratory. The beautiful re 

 searches of Radziszewski show us the possibility of such a thing. Still 

 it is yet to be proven that these same processes occur in the bacterium 

 and are responsible for its luminesence. I see no warrant for Beijerinck's 

 assumption that light is produced by sudden union of oxygen and pep 

 tone at the moment of conversion into living protoplasm. To begin 

 with, it is still to be demonstrated that peptone is capable of direct con 

 version into protoplasm. Sny thesis is not always a recapitulation of 

 analysis. 



To me it seems that luminescence is connected with metabolism, and 

 since its appearance is closely followed by the presence in the culture 

 liquid of the products of portein decomposition, that it is a phase of 

 destructive metabolism. It also seems highly probable that the phe 

 nomenon of contractility (motility) and luminescence are closely related 

 to one another, since the one appears when the other disappears. Fur 

 ther, it seems possible that the sodium ion may serve as a strongly 

 reducing agent, possibly rendering oxygen atomic and so providing for a 

 very active oxidation with consequent liberation of energy as light. 



In the near future I expect to be able to test the hypothesis suggested 

 in the latter part of this paper. 



Summary. 



In conclusion I may summarize the chief results of the experiments as 

 follows: 



1. All acids are injurious to light production. A slight excess of alkali 

 is even more injurious than a slight excess of an acid. 



2. The temperature limits for light emission are within those necessary 

 for growth. 



3. Change of temperature, either sudden or gradual, is without effect 

 on luminescence, i. e., does not stimulate. 



