ACTION OF CYTOST 137 



substances which must attain a definite concentration 

 in the cells before active growth ensues. These and 

 other explanations have been reviewed by Buchanan 

 and Fulmer (1928), and we shall not therefore elab- 

 orate upon these ideas. 



If, as suggested above, some accelerating substance 

 is necessary for the rapid growth of bacteria, they can, 

 if supplied with adequate food and kept in an optimal 

 physical environment, synthesize this substance for 

 themselves. This becomes self-evident when one re- 

 calls that cultures of bacteria may be obtained from a 

 single bacterium isolated by the micro-pipette method 

 first introduced by Barber (1904). In this respect, 

 then, the bacteria differ from the somatic tissues of 

 higher animals, which, as found in tissue culture ex- 

 periments, demand a source of preformed cytost, 

 trephone, archusia, or whatever one prefers to call 

 the growth-accelerating substance. 



This is not surprising, considering the relatively 

 undifferentiated nature of bacteria and their lowly 

 position in the scale of life. Nevertheless, it is of in- 

 terest to ascertain if cytost prepared from bacteria 

 is capable of accelerating the growth of such or- 

 ganisms. 



For this purpose the author selected Bacillus coli 

 communis, since, in the course of another investiga- 

 tion in 1912, he had accumulated some 80 grams of 

 the dried organisms, which had been grown in mass 

 culture on solid synthetic media. As the colonies had 

 been removed from the surface of the latter by scrap- 

 ing, the mass of organisms was undoubtedly contami- 

 nated with some of the media. This unfortunately 

 could not be avoided with the facilities at the author's 



