CELLULAR STRUCTURE OF ORGANISMS 



97 



ment from the substance upon which the molds are growing. 

 Although the threads are very delicate, they can by growth 

 force their way through the substance upon which they are 

 feeding until they penetrate into the bread, or slice of lemon, 



FIG. 42. VARIOUS MOLDS 



A, a colony of Penicillium, showing the fruiting spore-bearing masses arising from the 

 mycelium; B, a bit of the colony more highly magnified; C, one of the fruiting masses, form- 

 ing spores; D, a colony of Mucor; E, the sporangia of Mucor, with the spores emerging, and 

 showing also the mycelium below not divided into cells; F, a bit of the colony of Asper- 

 gillus, showing a third method of formation of spores. 



or decaying apple, for some distance, and the material thus 

 becomes permeated with the mycelium. Careful study of the 

 threads of this mycelium with a high magnifying power shows 

 that they are made up of many cells. Cross partitions divide 

 the threads at intervals and separate the consecutive cells; 

 Fig. 42 B. The contents of each cell include protoplasm 

 and a nucleus. There is no differentiation of the cells, all in 



