MUCOR AND RHIZ0P17S 



87 



phores (i.e., a main stem with lateral branches) as in Fig. 36; and the 

 Cymomucors, with sporangiophores typically branched as in Mucor 

 circinelloidcs (Fig. 38) but frequently rather irregularly branched. 

 Zycha uses in his scheme of classification the presence or the ab- 

 sence of thallospores (Kugelgemmen) and Naumov uses the color 

 of the colony mycelial growth and specialized organs. Neither of 

 these two later workers puts so much stress on the branching of the 

 sporophore. Otherwise, the characters used for identification of 

 species of Mucor are much the same as those used by Lendner. 



Fig. 37. Mucor racemosus. Production of oidia by submersed mycelium, and 

 multiplication of these by budding. Photomicrograph by dark field illumination. 



The same authorities are to be consulted for identification of 

 species of Rhizopus. Zycha is much more conservative in his tax- 

 onomy in this genus. He recognizes only 8 species, whereas Lendner 

 describes 22 and Naumov some 30 species. 



M. Mucedo, being easily obtainable if fresh horse manure is incu- 

 bated in a moist chamber, is perhaps the best-known species of 

 Mucor. It has frequently been chosen as a type of the genus in 

 physiological experiments. It is proteolytic and also capable of 

 splitting fats. It is a cause of spoilage of various foodstuffs at times, 

 is supposed to play a part in the ripening of snuff, may cause a decom- 

 position of leather, and is found in retting flax. It may be recog- 

 nized by the unbranched sporangiophore and cylindrical columella. 

 No oidia or chlamydospores are formed. It is heterothallic. See 

 Fig. 25. 



