RANCIDITY OF FATS. 199 



product, and is prepared from sweet cream, which, before churning, 

 is heated to nearly 100 C. and then rapidly cooled again, whereby 

 the fission fungi just mentioned are killed. The bacteria which, 

 split up the glycerides in butter include one which R. KRUEGER (I.) 

 isolated from butter that had become cheesy, and which he named 

 Bacillus fluorescens non liquefaciens. 



Investigations on the breaking up of fats by bacteria, which 

 process is of medical interest in connection with the putrefaction 

 of dead animals, were conducted by G. VON SOMMARUGA (I.), chiefly 

 with pathogenic species, only a few of which were found to pos- 

 sess this power. Among these may be mentioned Bacillus typhi 

 abdominalis, B. pyocya?ieus, Micrococcus tetragenus, Vibrio cholera? 

 asiaticce, Denecke's spirillum, and others. On the other hand, 

 Bacillus megatherium and B. subtilis do not possess it. 



