46 



ELEMENTARY STUDIES IN BOTANY 



diphtheria '(Fig. 24, C), tuberculosis, and pneumonia, as 

 well as some very destructive plant diseases, are caused by 

 these bacteria. 



Other bacteria live in the soil, and are of enormous im- 

 portance in changing the materials of the soil and in adding 

 new material to the soil, making it possible for other plants 

 to use the soil. The great importance of these bacteria to 

 agriculture is coming to be recognized. 



38. True Fungi. The bodies of true Fungi consist of 

 filaments, which may be interwoven more or less compactly. 

 For example, the weav- 

 ing may be so loose 

 that the body is as 

 delicate as a spider 

 web, or it may be so 

 close that the body is 

 almost as compact 

 as felt. This filamen- 

 tous body is called a 

 mycelium (Fig. 25). 



Molds. The ordi- 

 nary mold that ap- 

 pears as a white furry 

 growth on stale bread 

 (when kept moist and 

 warm) may be taken 

 as an illustration (Fig. 25). The mycelium must be 

 related to its food supply, and therefore it is observed 

 spreading over the surface of the bread, evidently being 

 a true saprophyte. Branches from the mycelium penetrate 

 the bread, and into them the nutrient solution from the 

 bread passes. These branches that receive the food supply 

 are called hausloria (" suckers "), and of course are a very 

 essential part of the vegetative body. 



Under suitable conditions, the prostrate mycelium also 



FIG. 26. Section of a 

 sporangium of Mucor 

 developing, and show- 

 ing how the partition 

 wall is pushed up into 

 the cavity of the 

 sporangium. 



FIG. 27. Section of a 

 mature sporangium 

 of Mucor, showing 

 the spores. 



