LIFE HISTORIES OF FUNGI 



261 



meet, the dense protoplasm has been cut up into innumer- 

 able, more or less angular masses, each surrounded by a 

 plasma-membrane, and containing from two to six nuclei 



FIG. 187. Rhizopus nigricans. i, Full-sized sporangium, showing 

 layer of vacuoles nearly formed along the inner surface of the denser plasm, 

 X about 200. 2, Section passing to one side of the sporangiophore, 

 showing columella-cleft being formed by fusion of the vacuoles shown in i, 

 and by a furrow from the base of the sporangium, X about 200; 3, Detail 

 of another part of same sporangium as shown in 2, showing early cleavage 

 furrows, X about 850. (After D. B. Swingle.) (Cf. Figs. 186 and 188). 



each (Fig. 187). These finally become entirely separated 

 from each other, oval in shape, and surrounded by a wall 

 of fungus cellulose (chitin?) having clearly marked ridges 

 (Fig. 188). They are asexual spores, but differ from the 



