BACTEKIA. 



65 



morphous swollen forms (Fig. 18) are produced. It is not till then 

 that the threads are divided into small links, thus giving rise to 

 the typical chains. Only the thickest parts of the swollen 

 threads remain undivided and are at last dissolved. Thus the 



FIG. 18. Bacterium Pasteurianum. Transformation of the thread-forms and chains 

 after cultivation in " double beer" at about 34 C. (After HANSKN.) 



swollen forms play a regular part in the cycle of changes. 

 This cycle furnishes a striking example of the effect of 

 temperature in determining the form assumed by bacteria. 



The species Bacterium aceti and Bacterium Pasteurianum 

 differ, according to LAFAR, both chemically and chemico- 

 physiologically. In sterilised beer they give different fermen- 



