I 



MORPHOLOGY OF THE GENUS ACTINOMYCES. II 



Charles Drechsler 



(with plates ii-ix) 

 Taxonomy of species 



The obscurity that has surrounded the morphology of 

 Actinomyces, besides involving the genus in improbable specula- 

 tions concerning its phylogenetic relationship to the bacteria, has 

 brought about also a most unfortunate condition in the taxonomy 

 of the many described species. Most of the work on the genus has 

 been done by investigators with bacteriological inclinations, and 

 even where this has not been true, the prevalent view of the nature 

 of these minute plants has lead to the adoption of methods scarcely 

 applicable to mycological research. A discussion of characteristics 

 like the occurrence of endospores, flagella, capsules, sheaths, and 

 involution forms, caimot be regarded as constituting a morpho- 

 logical treatment more satisfactory for species of Actinomyces than 

 for species of Mucor or Boletus. 



The dependence of certain biochemical processes, particularly 

 chromogenesis, on definite conditions of nutrition, and the con- 

 spicuous differences resulting from comparatively slight changes 

 in the substratum, have long been noted by students of Actitiomyces, 

 yet descriptions of new species have continued to appear, based 

 largely and often quite exclusively, on these variable activities. 

 Very frequently writers have not compared their organisms with 

 others reported by previous investigators; and in recent years 

 there has been a tendency to disregard altogether the taxonomic 

 contributions of the preceding decades. Moreover, while identi- 

 ties have frequently not been recognized where they existed, in 

 other cases organisms have been supposed to be identical on 

 extremely slight evidence. One of these cases that has led to an 

 unusual measure of confusion is that of Gasperini's Actinomyces 

 chromogenus. This species was identified by both Gasperini and 

 Rossi-DoRiA (19) with an organism isolated from the air by the 

 147] [Botanical Gazette, vol. 67 



