Waksman — 54 — Actinomycetes 



The mycelium of actinomycetes produces true branching of a mono- 

 podial type. Some observers have reported dichotomous branching 

 (98), a phenomenon considered by others as uncertain (97). 



The formation, by certain species, of nodes from which side 

 branches are produced in the form of whirls has been reported by 

 Waksman for S. reticuU; this was later confirmed by others, notably 

 by Kriss (242), who added another species under the name of S. verti- 

 cillatus. 



The formation of short side branches which give rise to single spores 

 is characteristic of species belonging to the genus Microvionospora. 

 These spores have often been designated as chlamydospores or mega- 

 spores. Jensen (186) looked upon them, however, not as involution 

 forms but merely as a type of development of rod-shaped cells, often 

 observed among the mycobacteria and the corynebacteria. 



Fig. 12 c (see p. 52). 



Among species of Nocardia, Lieske observed the production of 

 swollen cells, which he considered as involution forms. Krassilnikov 

 considered these as normal stages in the life cycle of the organisms. 



In old cultures, certain swellings of the terminal ends of the hyphae 

 may be observed. These may also be formed under abnormal growth 

 conditions, as in concentrated media or in the presence of substances 

 like caffeine. These swellings may be considered as involution forms, 

 somewhat similar to the clubs produced by pathogenic actinomycetes in 

 the animal body. The separation of actinomycetes on the basis of 

 these formations is open to criticism. 



Plasmolysis has not been established as yet for the actinomycetes 

 with any degree of certainty. The lytic reactions are due either to auto- 

 lytic enzymes or to specific phages. 



Sporulation of Actinomycetes:— 



Spore forviation.— The actinomvces spore has been described as con- 

 taining a spherical, relatively large chromatin body which is surrounded 



