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TEXTBOOK OF BOTANY 



79. A Mold Plant (Fig. 22). — We can see with the aid of 

 a hand lens that the body of the bread mold is made up of 

 threads, somewhat hke those of Spirogyra, but branching 

 abundantly, light-colored when young and darker or almost 

 black when old. If we pick off a piece of a young mold 

 plant and examine it under the microscope, we find that the 



Fig. 22. — Part o£ a bread mold plant; 0, downward-growing branches 

 which obtain food for the plant; b, a horizontal branch; c, young spore 

 sacs, borne at the ends of upright branches ; d, an older spore sac contain- 

 ing ripe spores ; e and /, broken spore sacs from which the spores have 

 escaped ; in /, the internal dome-shaped wall has collapsed. 



threads are not divided by cross walls. In fact, the whole 

 plant — making, with all its branches, a large, interlacing struc- 

 ture — is, at least while it is comparatively young and 

 growing rapidly, a single cell. This cell is much larger as well 

 as more complex in form than any cell we have yet studied. 

 The branches of the plant are of two kinds : horizontal ones 

 (Fig. 22, fc) which grow upon or near the surface of the bread, 

 and others that grow in groups from the horizontal branches 

 downward into the substance of the bread (Fig. 22, a). 



