PATHOGENIC TRICHOMYCETES 267 



and should be differentiated from the spores of the lower bacterial 

 forms since they do not possess the same high resistance and serve 

 only to reproduce the species. The forms known to be pathogenic 

 for man may be arranged in four main groups : 



1. Leptothrix. Almost straight thread-like growth. No 



branching. 



2. Cladothrix. False branching. 



3. Nocardia. True branching. Reproductive elements. 



4. Actinomyces. True branching. Characteristic wreath- 



like growth in tissues. 



Leptothrix. Suppurative conditions of the mouth have been 

 reported as due to a member of this class. Investigators have 

 considered that Leptothrix buccalis, a form frequently found in 

 normal mouths, may under certain conditions become pathogenic. 

 Since the organisms have been so little studied, however, con- 

 firmatory evidence has not yet been obtained. 



Cladothrix. Several infections have been reported as due to 

 this group, but some difficulty has been experienced in deciding 

 whether the organisms should be classed as cladothrix or nocardia, 

 since the only morphological difference existing between the two 

 forms is that of true or false branching. An organism isolated at 

 autopsy by Eppinger from a chronic cerebral abscess which had 

 resulted in purulent meningitis was considered to show false branch- 

 ing and given the name cladothrix asteroides. On artificial media 

 it developed a delicate fungoid growth, and in rabbits and guinea 

 pigs it produced an infection similar to that observed in a number 

 of lung infections usually designated " pseudotuberculosis." 



Nocardia. The group is perhaps more frequently named 

 streptothrix, although according to the rules of nomenclature 

 the name is not applicable since it was given as early as 1839 to a 

 species of mold. Trevisan in 1889 suggested the name nocardia 

 in its place for the organism discovered by Nocard in farcin des 

 boeufs. Nocardia have been found in brain abscesses, meningitis, 

 wound infections, and pneumonic conditions. Consolidated areas 

 in the lungs and nodular formations have been found which clini- 



