138 THE ACTION OF THE LIVING CELL 



disposal. In consequence, in the experiments to be 

 cited presently, the possibility exists that the observed 

 effects were in part due to an enrichment of the media 

 by this means. This objection, however, seems of 

 doubtful significance, in vievv^ of the fact that the 

 amount of additional nutriment introduced into the 

 medium along with the cytost must have been of a 

 negligible order. 



Cytost was prepared from the dried B. colt men- 

 tioned above by autoclaving 1 gram of the dried or- 

 ganisms with 10 cc. of water. Plates were poured with 

 5 cc. of nutrient agar to which had been added 0.1 cc. 

 of the aqueous extract of dried B. colt. These plates 

 and controls were then inoculated with a standard 

 loopful of a 24 hour broth culture of B. coli. After 

 24 hours, the plates made with the bacterial cytost 

 showed a much better growth than the controls. Simi- 

 lar results were obtained using 0.15 cc. of the B. coli 

 cytost per 5 cc. of medium. It seems therefore that 

 although cytost is not essential to the growth of these 

 organisms, its presence in the medium accelerates the 

 growth of the latter. 



Similar concentrations of B. coli cytost added to 

 cultures of staphylococcus and streptococcus in nutri- 

 ent media failed to cause any observable increase in 

 growth; hence the specificity of cytost is apparent in 

 even such lowly forms as the bacteria. 



