110 MICRO-ORGANISMS AND FERMENTATION. 



at their upper extremities conidia of very varying forms 

 spherical, oval, cylindrical, straight, or curved. The systematic 

 position of the mould and its possible genetic connection 

 with other known fungi is just as little established as its 

 influence on nutritive liquids. Eriksson states that rye is 

 sometimes attacked by Cladosporium, and that the mould, 

 consumed in bread made from rye, or in beer, may give rise to 

 diseases in the human being. 



Concerning these, or at least closely-related forms, Zopf 

 described exact morphological investigations with numerous 

 illustrations in his memoir on Fumago, and also in his work on 

 the fungi. These last-mentioned black, dew-like fungi occur 

 very frequently on parts of plants. Frank correctly says : 

 " We are still quite in the dark with regard to specific 

 differences, the reason of which is especially to be found in 

 the frequent polymorphism of these organisms, and in the 

 fact that the different evolution-forms are scarcely ever 

 found together." 



