CHAPTER XXXVI 



ACTINOMYCES GROUP 



THE members of this group are often called Trichomycetes 

 or thread fungi. In many of their morphological characters 

 they resemble bacteria. Frequently they occur as short rods that 

 cannot be differentiated by examination from true bacilli. Usually, 

 however, they occur in threads, which in some genera may be 

 branched. These threads may show more or less differentiation 

 into parts, and certain portions may develop into conidia or spores. 

 These organisms show a more complex life history, therefore, than 

 do the true bacteria. On the other hand, they can scarcely be 

 grouped with the true molds, as they are much simpler in structure. 

 They may be considered as a group, therefore, related closely to 

 both bacteria and molds, and partaking of the nature of each. 



These organisms show such diversity of morphology in the 

 animal body and in culture-media that a satisfactory classifica- 

 tion into species and genera is a difficult problem. Many generic 

 names have been proposed. Some of these are valid, but the 

 organisms belonging to them are non-pathogenic, so far as known. 

 Jordan, in his General Bacteriology, has given a fairly satisfactory 

 working classification for the genera of the trichomycetes. 



Filaments showing no branching Lcjtlot/iri.r. 



Filaments showing false branching ('ludothr/.r. 



Filaments showing true branching: 



Spores or conidia produced Noc<ir<lin 



No spores demonstrated Actinomyces 



The genus name Streptothrix is also frequently used for the 

 genera given above as Nocardia and Actinomyces. This name, 

 however, was applied to an entirely different genus of plants by 

 C'onla in 1839, and was first so used. Its retention as a genus 

 name in this group is, therefore, no longer tenable, in the opinion 

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