42 Structure and Classification of Micro-organisms 



The leptothrix is a very difficult organism to secure in culture. 

 The attempts of Vignal* and of Arustamoff f were successful, 

 but upon the usual culture-media the organisms grew very 

 sparingly. 



Cladothrix. These also produce long thread-like filaments, 

 but they occasionally show what is described as false branch- 

 ing; that is, branches seem to originate from the threads, 

 but no distinct connection between the thread and the ap- 

 parent branch obtains. None of the cladothrices is known 



Fig. 6. Streptothrix enteola. Film preparation from peptone-beef- 

 broth culture, fourteen days at 37 C. X 1000. (Foulerton.) 



to be pathogenic. They are frequently organisms of the at- 

 mospheric dust, and not infrequently appear as "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 pow- 

 dery (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 patho- 



* "Annales de physiologic," 1886. 



* Kolle and Wassermann, "Handbuch der Pathogenen Mikro- 

 organismen," 1903, n, p. 851; Wratsch,i889. 



