34 
FREDA M. BACHMANN 
ing about half of the sKde. This allows a part of the agar film, which 
is above the liquid, to dry firmly on the slide and so helps to prevent 
loss of the film. If the entire edge of the film becomes loose from the 
slide, the film is certain to be lost. I have introduced and removed 
all liquids rather slowly and very carefully with a pipette in order to 
prevent a rapid movement of the liquid from tearing the film. Some- 
times a portion of the film will be torn off, but more often the film 
remains attached to the slide throughout. 
After fixing, the films are washed and then stained. I have used 
Heidenhain's iron hematoxylin with excellent results. After staining, 
Fig. 2. Microphotograph of a colony of yeast, grown, fixed and stained on a micro- 
scopic slide. 
