54 



GEORGE ALFEED BAITSELL 



had been running ten days, the medium was changed to a 0.025 

 per cent solution of Liebig's extract of meat and the culture was 

 designated Sb. From this time (October 2, 1910) culture Sb was 

 kept on the 'constant' medium of beef extract. As far as one 



Oct. 

 1910 



Nov 



Dec. 



Jan. 

 1911 



Feb. 



Diagram 1 Graph giving the life history of Culture Sb, showing the average 

 daily rate of division of the four lines of the culture again averaged for ten daj^ per- 

 iods. Beef extract culture medium. Point marked X indicates the point at 

 which conjugation appeared in the stock of the culture. 



could judge by appearances of every kind, the medium was a favor- 

 ble one for this animal. The division rate of the culture when av- 

 eraged for ten day periods was never as low as two divisions per 

 day during the first four months and at times the division rate ex- 

 ceeded three divisions per day when averaged for the same period 



