DIPHTHERIA. 395 



with indented edges, sometimes with a distinctly radiated 

 appearance. It must be remarked that when sudden 

 transplantations are made from blood-serum to agar- 

 agar the growth resulting is meagre, but the oftener 

 this growth is transplanted to fresh agar-agar the more 

 luxuriant it becomes. 



The growth in gelatin puncture-cultures is character- 

 ized by small spherical colonies which develop along the 



a b c 



Fig. 85. — Diphtheria bacilli (from photographs taken by Prof. E. K. Dun- 

 ham, Carnegie Laboratory, New York): a, pseudo-bacillus; b, true bacillus; 

 c, pseudo-bacillus. 



entire length of the needle-track. The gelatin is not 

 liquefied. 



Upon the surface of gelatin plates the colonies that 

 develop do not attain anything like the size of the colo- 

 nies upon Loffler's mixture. They appear to the naked 

 eye as whitish points with smooth contents and regular 



