Growth of Bacteria. 



113 



54 (1801) 



The effect of the accessory substances of plant tissue upon growth 



of bacteria. 



By O. T. AVERY and HUGH J. MORGAN. 



[From the Hospital of The Rockefeller Institute for Medical 

 Research, New York City.] 



The study of the properties of blood upon which depends the 

 ability of the so-called hemoglobinophilic bacilli to grow in this 

 medium, has shown that these properties are related to at least 

 two factors which can be separately studied. Further studies 

 have shown that both of these factors are present in plant tissue, 

 (potato and banana), and that sterile unheated vegetable tissue 

 can replace blood in the cultivation of B. influenzae. These 

 observations have now been extended; yellow and white turnip, 

 carrot, beet, parsnip, and sweet potato, when added to fluid 

 media have been found to possess the same growth stimulating 

 action as white potato. 



It has been found that these vegetable tissues not only permit 

 the cultivation of the so-called hemoglobinophilic organisms, but 

 that they also greatly favor the growth of other entirely unrelated 

 organisms. For instance, in the case of pneumococcus, not only 

 is there a marked acceleration of growth, but a seeding too minute 

 to initiate growth in plain broth alone, will amply suffice to 

 induce abundant multiplication in the same medium to which 

 small pieces of sterile, unheated vegetable have been added. 

 Moreover in the plant tissue medium the zone of hydrogen-ion 

 concentration within which growth can be initiated is considerably 

 extended beyond the acid and alkaline limits of the optimal range 

 in ordinary bouillon. In addition certain other bacteria, which 

 ordinarily fail to grow in the presence of free oxygen, multiply in 

 a medium containing fresh plant tissue even though no precautions 

 are taken to exclude air. It is evident, therefore, that the presence 

 in media of certain substances contained in fresh plant tissue not 

 only supplies the necessary factors for growth of the hemoglobin- 

 ophilic bacilli, but furnishes the requisite requirements for the 

 cultivation of other bacteria which multiply only under certain 



