100 



MEDICAL MYCOLOGY 



(Brefeld 1881) on dung-, the sporangiopliore swells under the sporangium to 

 a large head. On the absorption of more water, the sporangiopliore bursts 

 at the point of insertion of the columella, shooting off the sporangium and 

 columella often to a height of one meter and with an audible sound. 



In the Mucoreae the sporangial wall consists fundamentally of cellulose 

 which subsequently is so inerusted with calcium oxalate crystals that it be- 

 comes fragile ; simultaneously the cellulose is hydrolyzed to a more soluble 

 hygroscopic compound, so that it finally dissolves and the crystals scatter. 

 In the majority of genera, only the base of the sporangial wall remains, form- 



Fig. 5. — Showing the development of the sporangium of Sporodinia grandis. (After Harper 1899.) 



ing a basal collar about the columella. In the Mortierelleae the wall is equally 

 soluble, but the oxalate crystals are not formed. In Piloholus it is cuticular- 

 ized, except at the base, and permanent. 



At first, most of the cytologic processes within the sporangium are the 

 same (Fig. 5, i). The content of the young swelling is divided into a central 

 zone, filled mainly by sap and penetrated by a few protoplasmic threads, and 

 a rich peripheral zone, containing most of the nuclei (Fig. 5, 2). The border 

 between the two is differentiated into a foamy protoplasmic layer permeated 

 by narrow, flattened vacuoles. These fuse laterally and form between the 

 vacuolate central portion and the protoplasmic periphery a cleavage cavity; 

 its bordering surfaces are covered with a plasma membrane which is thickened 



