﻿i 9 i6J HARDER-BACTERIA 517 



proportions of the different types sometimes changed markedly 

 in successive counts. Thus it was found that after heavy frosts 

 the small transparent colonies made up sometimes one-half or 

 more of the total number of colonies on the plates. In subsequent 

 counts they would gradually decrease in number. 



The actinomycetes and the spreaders did not seem to be 

 affected by the frost, being present on nearly every plate counted 

 during the winter. The chromogens were more irregular in their 

 occurrence and apparently were somewhat less abundant during 

 very cold periods. 



The writer wishes to express his indebtedness to Professor 

 E. B. Fred, University of Wisconsin, for helpful suggestions and 



