534 



H. J. SEARS AND LULU L. CASE 



Another fact, which is not indicated in the tables, but which 

 is very apparent to the person doing the counting, is that in 

 cases in which the very small colonies appear on both the Mi 



TABLE 2 



and M2 plates they are very much larger and more easily counted 

 on the latter. 



A qualitative examination of the minute colonies which were 

 the source of the errors described above revealed the fact that 



