392 



BACTERIOLOGY. 



1 per cent, of grape-sugar) ; in bouillon without glycerin, 

 and in bouillon to which a bit of hard-boiled egg has 

 been added, the morphology of the organism is about in- 

 termediate, in both size and outline, between the forms 

 seen upon glycerin agar-agar and upon Loffler's blood- 

 serum. There will appear about an equal number of 

 short segmented and longer, irregularly staining forms ; 

 but in general the longest are rarely as long as the long 

 forms seen on blood-serum, and throughout they are not 

 so conspicuous for the irregularity of their stainirg. 



FIG. 68. 



Bacterium diphtheria. A. Its morphology on glycerin-agar-agar. 

 B. Its morphology on Loftler's blood-serum, c. Its morphology on 

 acid blood-serum mixture. 



In cultures made upon two sets of nutrient agar-agar 

 tubes, differing only in the fact that one set contains 

 glycerin to the extent of 6 per cent., while the other set 

 contains none, a noticeable difference in morphology can 



