354 ACTINOMYCETES 



illustrates the suggested relationship to the bacteria and to the higher 

 fungi : 



{Mycobacterium, Corynebacterium -^ bacteria proper 

 Geotrichum — + the molds proper 



i 

 Yeasts 



Lieske places organisms of the type of Geotrichum very close to the 

 actinomycetes because of the fragmentation of the mycelium com- 

 mon to both groups. Vuillemin also held that these organisms were 

 closely related. 



Since the arthrospores or fragmentation spores of actinomycetes 

 resemble bacteria so closely, and since some species of actinomycetes 

 may at least temporarily fail to form mycelium and grow entirely 

 in a bacteria-like form, one might rationally assume that bacteria 

 bear the same relationship to actinomycetes as yeasts bear to larger 

 molds, i.e., that they represent actinomycetes which have perma- 

 nently lost the power to form mycelium. This may be considered 

 as very probably true for the acidfast bacteria and the diphtheroid 

 group. But it remains to be proved that the bacteria are themselves 

 phylogenetically a homogenous group, and therefore it would be un- 

 wise to assume a relationship of all bacteria to the actinomycetes. 

 It should be pointed out that the fungi too constitute a heterogeneous 

 group and monophyletic origin for all fungi is not accepted by all 

 mycologists. 



The following diagram may have some value in depicting the rela- 

 tionships of the various genera of the actinomycetes to each other 

 and to related organisms. It must be remembered that any attempts 

 to show phylogenetic relationships must be a subject of personal 

 judgment and opinion, and can never be certain. As Jaques Loeb is 

 said to have remarked, in refusing to discuss evolutionary theories, 

 "I do not know how to experiment with the past." 



Mycobacterium — acidfast Nocardia 1 



I > — Micromonospora 



Corynebacterium — non-acidfast Nocardia J 



Lactobacillus — Actinomyces 



Streptomyces 



Streptococcus, etc. Geotrichum — Moniliales 



Morphology of Actinomycetes. Actinomycetes differ from nearly 

 all the Eumycetes in the extreme fineness of their mycelium. This 

 varies from usually less than two microns in diameter to less than 

 one micron and is commonly about one micron. The mycelium is 



