The Higher Bacteria 39 



" weeds " in culture-media. The colonies grow to about a centimeter 

 in diameter, are usually white in color, irregularly rounded, sharp 

 at the edges, more or less concentric, dry and powdery (not 

 velvety) or scaly on the surface. They commonly liquefy gelatin 

 and blood-serum. 



Streptothrix. — These organisms certainly branch. They also form 

 endospores. Many of them can be cultivated. Not a few are 

 found under circumstances suggesting pathogenic action. For a long 

 time there has been a disposition to regard Bacillus tuberculosis as a 

 form of streptothrix, since old cultures show branching involution 

 forms. The old genus Actinomyces is also included by a number of 

 writers among the streptothrices, so that the Actinomyces bovis of 



Fig. 8. — Streptothrix enteola. Film preparation from peptone-beef-broth cul- 

 ture, fourteen days at 37° C. X 1000 (Foulerton). 



Bollinger is called Streptothrix actinomyces, the Actinomyces 

 madurae, Streptothrix madurae, and the organism found by Nocard 

 in the disease known as "farcin du bceuf," Streptothrix farcinica. 

 There seems, however, no adequate ground for this arrangement, 

 and the old genus Actinomyces should be kept, Eppinger found a 

 streptothrix in the pus of a cerebral abscess, and Petruschky, 

 Berestneff, Flexner, Norris, and Larkin have found streptothrices in 

 cases of pulmonary disease simulating tuberculosis. The organisms 

 described by these writers were not identical, so that there are prob- 

 ably several different species. They usually grow well upon 

 ordinary media and upon solid media form whitish, glistening, well- 

 circumscribed colonies attaining a diameter of several millimeters. 

 As they grow old they turn yellowish or brownish. They liquefy 

 gelatin. Some of the cultures were not harmful to the laboratory 

 animals, others caused suppuration. 



