60 



PRINCIPLES OF BACTERIOLOGY 



quarter of an inch square. The block is placed under surface down on 

 a slide and protected from dust. A suspension of the growth to be 

 examined is then made in sterile bouillon and spread over the upper 



FIG. 30 



FIG. 31 



FIG. 30. Irregular fringed colony (B. malignant cedema). (From Kolle and Wasserman.) 

 FIG. 31. Round surface colony (colon bacilli grown in stiff gelatin). 



FIG. 32 



FIG. 33 



FIG. 32. Colony of typhoid in rather stiff gelatin. 



FIG. 33. Colonies of typhoid and colon bacilli in rather soft gelatin. 



FIG. 34 



FIG. 35 



FIG. 34. Colony of colon bacilli grown in soft gelatin. 



FIG. 35. One irregular colony of colon and two of typhoid bacilli in soft gelatin. (Figs. 31-35 from 

 photographs by Dunham.) 



surface of the block. The slide and block are then put in the incubator 

 for ten minutes to dry slightly. A clean cover-slip is now placed on 

 the agar block in such a way as to avoid large air bubbles. The slide 



