BACTERIUM DIPHTHERIA 



485 



to which a bit of hard-boiled egg has been added, the mor- 

 phology of the organism is about intermediate, in both 

 size and outlines, 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 



FIG. 81 



A. 



Bacterium diphtheria. A, its morphology on glycerin-agar-agar; B, 

 its morphology on Loffler's blood-serum; (7, its morphology on acid blood- 

 serum mixture. 



are rarely as long as the long forms seen on blood-serum, 

 and throughout they are not so conspicuous for the irregu- 

 larity of their staining. 



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 



