A BACTERIOLOGICAL METHOD 
35 
the slides are washed in water, dehydrated with alcohol, using first a 
very dilute solution and lastly absolute alcohol, then rinsed in xylol 
and mounted in Canada balsam. The colonies are flat. This is 
especially desirable for a cytological study, because the cell structure 
is not obscured by anything in a higher or lower plane. The accom- 
panying text figure and microphotograph illustrate the smaller colonies 
on plates which have been incubated nine hours at 37° C. and stained 
with Heidenhain's iron alum hematoxylin. 
College of Agriculture, 
University of Wisconsin 
