MUCORALES 



103 



the differentiation of sporangial content into a sterile and a fertile zone and 

 the individualization of single spores, the sporangium also develops into 

 numerous "partial sporangia," each of which forms a .small number of 

 sporangiospores. 



In Syncephalastrum the ability to form sporangia of the Mucor type has 

 entirely disappeared, and the extramatrical partial sporangia have reached 

 a higher stage of development (Fig. 7). Several palmately joined sterigmata 

 develop into long cylindric tubes which receive as many as 20 nuclei each. 



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Fig-. 7. — 



Syncephalastrum cinereum. Development of extramatrical partial sporangia. (X950.) 

 (After Moreau 1914.) 



When these have reached their full length, their content splits into uni- or 

 multinucleate portions which round off and are surrounded by walls. The 

 spores are finally liberated by the dissolution of the sporangial wall (Thaxter 

 1897, Moreau 1913). 



In Syncephalis, after the destruction of the partial sporangium, the spores 

 remain connected with the adjacent cufflike part of the sporangial wall; the 

 spore wall itself remains thin and insignificant while the sporangial wall is 

 thick and occasionally sculptured. In S. aurantiaca, the partial sporangia 

 divide by septa into as many locules as there are spores. When these septa 



