ACTINOMYCETEAE 705 



groups, it seems extremely artificial as they use it. Their next subdivisions, 

 which are based on comparative pliysiology and staininji' reactions, are more 

 natural and have been followed in my key. 



Lieske (1921) provided much information but did not attempt any classi- 

 fication. 0rskov (1923) proposed to redefine Cohnistreptothrix to include 

 organisms which form a unicellular, nonseptate vegetative mycelium, and an 

 aerial mycelium composed of hyphae, thicker than those of the vegetative 

 mycelium and divided into spores of uniform size and shape. He retained 

 Actuiomyces for organisms in which the vegetative as well as the aerial myce- 

 lium divide by septa into pieces of irregular size and shape without any spores, 

 as in hi.s Cohnisireptoihrix. He created a new genus, Micvomonospora, for 

 organisms which form a unicellular mycelium without aerial hyphae but with 

 spores borne singly on the tips of short branches of the vegetative hyphae. 

 This classification by 0rskov is a step in the right direction, but it is obviously 

 impossible to apply it to the pathogenic species in the present state of our 

 knowledge, almost none of which have been described morphologically with 

 sufficient care to place them. 1 suspect that when the morphology has been 

 carefully studied, the Majoves of Chalmers & Christopherson will be found to 

 belong in Cohnistreptothrix of 0rskov not of others, their Minores in his 

 Actinomyces, and their Breves in his Micvomonospora with a certain amount 

 of redefinition and readjustment. Jensen accepts 0rskov's classification for 

 his soil organisms, adding to the nomenclatural confusion by replacing 

 Cohnistreptothrix 0rskov by Actinomyces, and Actinomyces 0rskov by Proacti- 

 nomyces. He includes Corynehactevium, Mycohacterium, and his Proactinomyces 

 in his Proactinomycetaceae, leaving Actinomyces and Micvomonospora for his 

 Actinomycetaceae. 



While is it quite possible that Corynehacterium and Mycohacterium may 

 sometime be shown to belong to this group, the literature on these genera is 

 so extensive and well known to the medical man that no attempt will be made 

 to cover it in this work. 



Since so little morphologic work has been done on this group, it seems 

 wiser to leave all the species in Actinomyces than to attempt a separation. 

 Cohnistreptothrix has been used for the anaerobic species, but in the present 

 chaotic state of the literature it is difficult to separate strict anaerobes from 

 partial anaerobes. ActinobacilUis is recognized by Buchanan, Bergej^ and 

 others as a distinct genus. Its morphology needs further study before its 

 systematic position will be clear. Malhranchea was proposed many years ago 

 and recently revived by Vuillemin. It is not distinguishable from many species 

 of Actinomyces, in fact it shows the characteristic morphology of that genus. 



ACTINOMYCES 



Actinomyces Harz, Jahresber. Miinchener Central-Thierarzneischule 1877: 

 125-140, 1877. 



Streptothrix Cohn, Beitr. Biol. Pflanzen 2: 186, 1875, non Corda, Pracht- 

 flora Europ. Schimmelbildungen 27, 1839. 



