ALTERNARIA 



113 



Candida species. In later subcultures mycelium also develops under 

 aerobic conditions, the growth becoming tougher in consistency, and 

 eventually producing an olive-green aerial mycelium which gives 

 rise to branched chains of conidia. 



The aerial conidial apparatus closely resembles that of Clado- 

 sporium, the color also being the same. Hansen was of the opinion 

 that these black yeasts are but yeast-like growth forms of dematia- 

 ceous molds of the type of Cladosporium, and this view was also 

 supported by Lindner. Henrici also concurred in this opinion. 

 Several of the strains which were 

 examined by Henrici produced, at 

 times from the' pasty yeast-like 

 growth, at times from the aerial 

 mycelium, characteristic two- 

 celled conidia exactly like those of 

 Cladosporium. This is probably 

 the explanation for the use of the 

 generic name Schizosaccharomy- 

 ces by Marpmann. 



The above paragraphs are es- 

 sentially as Henrici wrote them in 

 1930. Since then Henrici and one 

 of us have isolated several more 

 strains of these organisms. For 

 the most part, the "degeneration" 

 (see Chapter II) was as described. In some cases, for long periods 

 of time, they "degenerated" into the form known as Torula nigra, 

 that is, they formed chains of round black spores directly from the 

 mycelium or from short lateral branches. Unlike in Cladosporium, 

 the chains did not branch. Later, some of these strains appeared 

 wdth branched chains of conidia as in Cladosporium but we have 

 some strains that still show the Torula type of growth. This whole 

 group seems poorly understood but it seems clear that the "black 

 yeasts" are but a unicellular growth phase of certain of the Demat- 

 iaceae including Cladosporium and possibly other genera as well. 

 See Chapter 11. 



Alternaria. Members of this genus are also frequently encoun- 

 tered by the bacteriologist. They form dark olive-green or brown 

 colonies similar to those of Cladosporium, save that the aerial my- 

 celium is much looser, forming a more woolly type of growth. 



Molds of this group may be recognized by the peculiar spores of 

 rather large size, multichambered, and composed of a number of 



Fig. 65. "Torula nigra." When first 

 isolated from soil, it grew as a bud- 

 ding 3'east without mycelium. 



