96 MYCOLOGY 



Zygospores were formed in one week where the aerial radiating hyphae 

 had come into contact. By this experiment all influences exerted 

 through the solid culture media, or which were due to contact of vege- 

 tative mycelia, were eliminated. 



The sporangia of Mucor mucedo are raised upon the ends of sporangio- 

 phores. When fully formed the sporangium consists of a wall beset 

 with spicules of calcium oxalate, the spores separated from each other 

 by a slimy intersporal substance (zwischensubstanz), and a columella 

 which projects into the interior of the sporangium. The formation of 

 spores in Rhizopus nigricans and Phycomyces nitens has been studied by 

 Swingle,^ who finds that the columella is formed by the cutting upward 

 of a circular surface furrow or cleft, thus cleaving out the columella over 

 the end of which a plasma membrane is formed. The spore plasm of 

 Rhizopus divides into spores by furrows pushing progressively inward 

 from the surface and outward from the columella cleft both systems 

 branching, curving and intersecting to form multinucleated bits of pro- 

 toplasm (the spores) surrounded only by plasma membranes, which 

 become the spore walls and separated by spaces filled with the inter- 

 sporal substance (zwischen substanz). The endospores, or sporangio- 

 spores, of Rhizopus nigricans and Sporodinia grandis are multinucleate, 

 while those of Pilobolus are binucleate, according to Harper. The es- 

 cape of the mature sporangiospores takes place when a portion of the 

 sporangial wall is dissolved. The spores escape imbedded in the inter- 

 sporal slime, which dries up liberating the spores. Certain species of 

 Mucor are capable of fermenting grape juice, the power of fermentation 

 depending on the species. The following species produce alcoholic fer- 

 mentation (Lindner) : 



Quantity of alcohol 

 Species by volume, 



per cent. 



Mucor Jansscni 3.41 



Mucor lamprosporus 3.71 



Mucor javanicus 2 . 83 



Mucor phimbeus 4.62 



Mucor pirelloides i • 06 



Mucor racemosus 462 



Mucor Rotixianus 5.25 



Mucor griseo-cyanus 4 . 00 



Mucor genevcnsis 5-2i 



'Swingle, DeanB.: Formation of the Spores in the Sporangia of Rhizopus 



nigricans and of Phycomyces nitens. Bull, jy, Bureau of Plant Industry, 1903. 



