242 



SELMAN A. WAKSMAN AND J. S. JOFFE 



On repeated transfer, the culture was found to deteriorate 

 since it took a longer period of time to develop. It was found, 

 necessary, in order to obtain a good growth, to use a sterile 

 pipette instead of a loop, one or two drops being sufficient to 

 inoculate 100 cc. By buffering the medium with suitable sub- 

 stances, such as phosphates, the organism would develop much 

 more rapidly, particularly at the more acid reactions. The 



1^ 



0, 



P^ curve 



per cent soluble P curve 



*^ ptr/od of mctft^at/oPi /n ^ay. 



I 



Fio.l. CourseofReaction AND Accumulation OF Water Soluble Phosphates 

 IN A Pure Culture of Thiobacilliis thiooxidians n. sp. 



organism was found to be morphologically similar to the two 

 ThiobaciUi described by Beijerinck, and it is, therefore, classified 

 in that genus, under the name of Thiohacilliis thiooxidans n. sp. 

 Morphology. Vegetative cells, on the synthetic media used, 

 are short rods, with rounded ends, usually occurring singl}', to 

 some extent in pairs and rarely in triplets. The majority are 

 less than 1 micron long and about 0.5 micron in diameter. Spore 

 formation, absent. The majority of the cells are non-motile, 

 although a few motile cells can also be found in young (seven 



