178 MORPHOLOGY. 



After mounting a small quantity of the mycelium bearing these 

 heads, if we have been careful to take it where the heads appear 

 quite young, it may be possible to study the early stages of their 



Fig. 190. 

 Portion of banana with a mould (Rhizopus nigricans) growing on one end. 



development. We shall probably note at once that the stalks or 

 upright threads which support the heads are stouter than the 

 threads of the mycelium. 



These upright threads soon have formed near the end a cross 

 wall which separates the protoplasm in the end from the remain- 

 der. This end cell now enlarges into a vesicle of considerable 

 size, the head as it appears, but to which is applied the name of 

 sporangium (sometimes called gonidangium), because it encloses 

 the gonidia. 



At the same time that this end cell is enlarging the cross wall 

 is arching up into the interior. This forms the columella. All 

 the . protoplasm in the sporangium now divides into gonidia. 

 These are small rounded or oval bodies. The wall of the spo- 



