THALLOPHYTA— FUNGI 



78 



Besides these sexual and asexual modes of reproduction, vege- 

 tative reproduction very commonly occurs. In forma such as 

 Bacteria and yeast it is much the most general method, and 

 consists only of ordinary cell-divisions, the daughter cells at 

 once separating from the one which gives rise to them. Some- 

 times in yeast this separation does not at once take place, with 

 the result that chains of cells are produced [fig. 827). 



Fig. 824. 



Pig. 825. 



Pig. 826. 



Fig. 824. Stylogonidia or stylospores of E urotium, f oi-med by repeated absbric- 



tion from the basal cell. After Dodel-Port. Fig. 825. Teleatospores of 



Pacdn ia graminis bursting through epidermis of straw. After Dobel-Port. 



Fig. 826. Two gonidacgia of Achlya. A. Closed. B. Eiiptured, and 



allowing the zoogonidia a to escape, b. Mother cells of the latter after 

 escape of e, the zoogonidia, from them. Fig. 827. Two yeast cells bud- 

 ding. 



In other cases a hypha divides by the formation of transverse 

 septa into a number of cells, each of which becomes rounded 

 off, and the chain breaks up into single cells which are capable 

 of immediate germiuation. They are often called oidium cells. 

 More complex forms are the bodies known as sclerotia, which are 

 composed of a mass of hyphse closely felted together and covered 

 by a pseudo- cortex. These separate from the mycehum which 



