CLADOSPORIUM HEEBARUM. 



377 



budding capacity of a conidium is not confined to the formation 



of a single daughter conidium, a second adjacent bud being 



oftentimes formed, which is capable of 



acting in the same way, and thus a 



richly branched formation ensues, as 



shown in the course of development in 



Fig. 1 86. The basipetal constriction of 



conidia by Penicillium glaucum, on the 



other hand, is naturally incapable of 



such a method of development, and is 



confined to the formation of a simple 



conidial chain. 



According to the observations of 

 JANCZEWSKI (II.) a considerable degree 

 of variation prevails in respect of the 

 dimensions of the mycelium and the 

 conidia of Cladosporium herbarum, a 

 circumstance explaining the practice of 

 classifying these various forms as dif- 

 ferent species, before this diversity was 

 recognised. Thus, the length of the 

 ordinary ovoid conidia (Fig. 187) varies 

 from 12 to 25 p, and the breadth from 

 5 to i o P-. The dimensions of the mycelial 

 filaments vary accordingly, so that one 

 worker may be confronted with a giant 

 form, whilst another may have a dwarf 

 specimen. The number of septa within 

 the conidia also varies with the age ; 

 two being present in one case, whilst 

 another cell contains only one, and a 

 third exhibits none at all. The external 

 surface of the brown or olive-green 

 membrane of the conidia may be covered 

 with fine needles (crystals ?), though 

 oftentimes it is smooth. On the basis 

 of this characteristic, the systematist 

 has elaborated various species of Clado- 

 sporium ; but in the present state of 

 knowledge we cannot say whether these 

 are specifically distinct forms or only 

 caused by differences of environment. 



The above-described conidiophores 

 are often found in black mildew on 

 dead parts of plants, on damp cellar 



walls, casks and vats, the surfaces of these being covered with a 

 herbage which is light olive-green when young, but gradually 

 passes through olive-brown into dark brown. Simultaneously 



FIG. 185. Mycosphaerella 



Tulasnei (E. Jancz.). 



Mycelial filament with conidia. 



{After Janc'.ewski.) 



Mag-n. 250. 



