Fig. 27. 



Stained film specimen of the bubo fluid of a protected guinea-pig, 

 the plague bacilli as involution forms. x 1000. 



Fig. 28. 



Young colonies of B. pestis on the surface of a gelatine plate, after 

 several days' incubation ; the colonies are raised, conical in the centre, filmy 

 and irregular at the margin, the centre granular or even filamentous. 

 xl7. 



