ISOLATING THE BACTERIAL PROTBIBS. 173 



myself. The coucentrated solution is then poured into 

 absolute alcohol, which precipitates the albumose and re- 

 moves any impurities that might be derived from the 

 methylated spirit. This prolonged treatment with alcohol 

 will tend to remove any free ptomaines or other substances 

 soluble in alcohol. Peptones and salts present in the cul- 

 ture liquid remained lor the most part in solution when 

 the albumose was precipitated with (NH^)2S04. No soluble 

 proteids (except traces of peptone) were present in the cul- 

 ture medium." 



Ordinarily the bacterial proteids are isolated by preci- 

 pitation with absolute alcohol, re-solution in water and re- 

 precipitation with alcohol. However, as has been stated, 

 TizzONi and Cattani find that strong alcohol destroys the 

 activity of the poison of their tetanus germ. The method 

 employed in obtaining the bacterial celhdar proteids has 

 already been given (see page 130). 



