406 ACTINOMYCETES. 



sometimes be recognized as a form or descendant of the 

 diphtheria bacterium, yet it was impossible by the employ- 

 ment of most various means to render it virulent, not even 

 by the simultaneous injection of streptococci. 



Important, but lacking confirmation, is the statement of 

 Hewlett and Knight that they have succeeded in the Lon- 

 don Institute of Preventive Medicine in converting the 

 Hofmann-Wellenhof organism into the virulent diphtheria 

 bacterium by passage through animals, and that typical 

 virulent diphtheria bacteria may be changed into the typi- 

 cal Hofmann-Wellenhof organisms by careful heating 

 (C. B. XXIII, 793). 



Corynebacterium xerosis. (Neisser and Kuschbert.) 

 L. and N. 



(Plates 58-60 in part.) 

 Xerosis bacillus of Neisser and Kuschbert. 

 Grows especially in short forms, yet Heinersdorff, for 

 example, represents a number which differ in no way from 

 diphtheria bacteria, and we have also often observed such 

 forms. According to all writers, the growth on Loffler's 

 serum is dry and more scanty than that of the diphtheria 

 bacterium, and still slower upon glycerin-agar (58, viii, c). 

 Upon potato no growth is to be seen. When magnified 

 sixty times, it is not distinguishable from feebly growing 

 forms of Coryn. diphtherise (60, viii). When grown on 

 Loffler's serum at 35° for nine to twenty-four hours, there 

 are none, or only a few, of Neisser' s granules. ^ Bouillon 

 always remains clear, and acid production usually is absent: 

 i. e., at most, 0.6 in twenty hours, about 1.0 in forty hours; 

 in sugar bouillon in twenty hours, 0.6-1.6; in forty hours 

 usually only 1-1.5, but may be as much as 3.2. In 

 numerous cultures from the eye and nose we usually 

 observed slight acid production parallel with the limited 

 growth, but sometimes, in spite of this, well-marked 

 granule staining. Pathogenesis is lacking, according to all 

 writers, and the organism appears to only accompany and 

 not cause the xerosis processes in the eye which are accom- 



' Not infrequently we found distinct granule staining, also in non- 

 virulent cultures which produced no acid and whose growths were dry 

 and scanty. 



