M(tHi'H()i.(»(i\'. (•^■'r( )!.()( ;^•. and ijfi; ('^■('M•:s 



91 



Tahi.k 15 

 Tcnlatirc plu/loi/inctic scheme of the Actinoini/celules (Jensen 1U53) 



First st;ij;o; 



rods, 

 somotinios: 

 l)i;mcliiiiK. 



^ Second stage: 

 mvrelium 



Third stage: 



mycolivim and 



spores 



Fourth stage: 



mycelium and 



sporangia 



Propioni bacterium 



Cory lie form 

 l)acteria 



Lactobacillus? 



Mj/cobacterium \Mt/rohacleriutn 

 uroup li j sensu strictu 



Actinomyces 



Nocardia 

 nonacid- 

 fast a 



Nocardia 

 acid- 

 fast a 



Nocardia 

 nonacid- 

 fast /3 



Nocardia 

 acid- 

 fast /3 



Micromonospora 



Streptomyces 



Actinoplanes 



from that of Eubacteriales. The important 

 difference bet\veen uctinomyces and nocardia 

 consists in the production by the former of 

 true reproductive spores and the occurrence 

 of a prolonged diploid phase, in contrast to 

 the occurrence, in the latter, of a microcyst 

 and a greatly reduced diploid phase. When 

 branching occurs in nocardia, it is not of the 

 permanent type but resembles that of an 

 actinomyces, and is thus differentiated from 

 permanent l)ranching. Both genera have a 

 well-marked haploid generation arising from 

 a spore by Vnidding, and a diploid one arising 

 from the initial cell. 



Webl) and Clark (1957) demonstrated the 

 existence in the growth cycle of N. corallina 

 of a unicellular, uninuclear coccoidal stage. 



By proper staining techniques, they ob- 

 served nuclear structures comparable to the 

 nuclei of higher organisms. Fragmentation 

 of the hyphae was preceded by cross-wall 

 formation, the first step of fragmentation 

 being the reorganization of the hyphal nuclei. 

 The formation of the cross walls was pre- 

 ceded by nuclear division. 



Further information on the early studies 

 of the nocardia group, their relationship to 

 the mycobacteria, and their morphological 

 changes is found in the work of Vierling, 

 Karwacki, Badian, Bisset, Hagedorn, and 

 numerous others. The life cycles of nocardias 

 have been chscussed further by Combes et at. 

 (1957). 



