D. J. DAVIS 657 



and various yeasts and related organisms like blastomyces or sporothrix, living or 

 dead, or extracts of these organisms, are rich in this substance. It will appear from 

 the foregoing facts that we are dealing with substances having many of the properties 

 of the vitamines — substances which we now recognize as necessary for the life and 

 growth of animals. 



In addition to these two special substances, other nutritive substances, such as 

 protein compounds or peptone, are necessary. Hemoglobin alone, which contains 

 both these bodies, will not support the growth of this organism. This suggests that 

 these two bodies do not themselves serve as food for the bacteria, but somehow 

 through their interaction control other nutritive processes of the organism. As to the 

 real nature of this process we know as much or as little as we know of the mechanism of 

 the action of vitamines in higher organisms. The possibility exists that through the 

 study of such processes in the lower and simpler forms of life we may be able to analyze 

 more clearly analogous or comparable processes in the higher forms. For example, it 

 would seem that in this process, as it concerns the influenza bacillus, the second sub- 

 stance somehow controls the metabolism of iron and through this element which is a 

 vital necessity for life-processes controls other metabolic activities, especially those 

 dependent upon oxidation changes. Similar substances may control metabolic proc- 

 esses dependent on other elements. 



As a result of the analysis of the peculiar nutrition of the influenza bacillus it is 

 now possible to explain satisfactorily the phenomenon of symbiosis or satellitism as 

 observed in this organism. When grown with another bacterium or yeast or with 

 plant or animal tissue, especially on plated media, the influenza bacilli near the foreign 

 tissue or organism will grow profusely, often forming large giant colonies. This is 

 explained thus: From the foreign organism or tissue there diffuses into the immediate 

 vicinity this second vitamine substance which in conjuction with the hemoglobin or 

 its derivatives furnishes the proper mechanism for the growth of the influenza bacil- 

 lus. In the absence of blood or hemoglobin no such stimulating effect is noted in media 

 about the foreign tissues or bacteria. 



It is interesting that the influenza organism or its extract will not stimulate it- 

 self. This at once suggests the use of this method in the identification and differentia- 

 tion of related bacteria about which there are disputed points. The pertussis bacillus, 

 the Morax-Axenfeld bacillus, the Ducrey bacillus of soft chancre, and the Koch- 

 Weeks bacillus all will stimulate the influenza bacfllus, and on this basis may be dif- 

 ferentiated from this organism. Many different strains of influenza bacilli of Pfeiffer, 

 for example, strains isolated during the epidemic, strains from influenza meningitis, 

 from various respiratory infections, and from normal throats, have been tested, and 

 all fail to reveal this symbiotic phenomenon toward one another. 



The distribution of the influenza bacillus is now fairly well known. Because of its 

 hemophilic property it cannot live long except in close association with the animal 

 body. In man it is a very common inhabitant, limited largely to the respiratory tract 

 in normal and pathological states. In its distribution in this tract it is somewhat sim- 

 ilar to the streptococcus hemolyticus. In normal throats in both adults and children 

 it occurs roughly in from 10 to 40 per cent or even higher, and often in large numbers. 



