ZYGOMYCETES 



103 



single spores, the sporangium also continues its development and 

 develops into numerous extrasporangial partial sporangia, each of which 

 forms a small number of sporangiospores. 



In Syncephalastrum racemosum and S. cinereum (Thaxter, 1897; 

 Moreau, 1913) the facultative formation of Mucor sporangia is entirely 

 lost; the extramatrical partial sporangia have reached a higher stage of 

 development. They develop several sterigmata, generally joined palm- 

 ately into long cylindrical tubes which take up as many as 20 nuclei 

 (Fig. 62, 1 and 2). When they have attained their full length, their 

 content splits simultaneously into uni- or multinucleate portions which 



Fig. 62. — Syncephalastrum cinereum. Development of extrasporangial partial sporangia. 



( X 740; after Moreau, 1914.) 



round off and are surrounded by membranes (Fig. 62, 3). These are 

 liberated by disintegration of the sporangial membrane. 



In Syncephalis, development goes still further (Tieghem, 1875; 

 Vuillemin, 1902). After the destruction of the partial sporangium, the 

 spores always remain connected with the adjacent cuff -like part of the 

 sporangial membrane; the spore wall itself remains thin and insignificant 

 while the sporangial wall is thick and occasionally sculptured. In S. 

 auraniiaca, the partial sporangia divide by septa into as many locules 

 as there are spores. By splitting these septa, they divide into oidial 

 members, each of which contains a spore ; thus the spores are completely 

 surrounded by a sporangial wall, inseparable from their own wall. 



