MUCOB MUCEDO. 317 



days. At other times, in order to obtain zygotes, it succeeds well 

 if the sowing is made in some drops of concentrated plum-juice 

 (e.g., of French plums), sterilised by long boiling, and then mixed 

 with 10 to 20 per cent, of absolute alcohol. The sowing is made 

 on a cover- glass in a damp chamber constructed of a glass ring 

 (see p. 279), and the object-slide placed in the large plaster of 

 Paris moist chamber (p. 279). 



That these zygospores actually belong to Mucor Mucedo can 

 be determined by germinating them. When the conditions for 

 their development are present, the zygospores are produced in 

 great number, and a large amount of material for investigation 

 can be obtained by cleansing the dung in question with water. 

 The ripe zygospores sink. They are carefully washed and laid 

 upon object-slides under a bell-jar with its edges immersed in 

 water. Germination begins in about six weeks, when each 

 zygospore emits usually one thick germ-tube, which is a sporan- 

 giophore, and is crowned by the characteristic sporangium of 

 Mucor (Fig. 114, E). For the emission of the germ-tube the 

 black outer wall of the zygote, the exosporium, is only torn 

 so far as is necessary ; the development of the sporangium 

 proceeds relatively slowly, and is completed about the third day 

 after the commencement of germination. 



" Mucor Yeast." Mucor can be grown also upon the surface 

 of a saccharine fluid, and forms submerged and aerial hyphae 

 as upon bread or dung. But if gondia are grown completely 

 submerged in such a fluid, as, for example, in the thin layer 

 between a cover-glass and a slide, the hyphae produced break 

 up by constriction into necklace-like strings, the units of which 

 separate and bud, much after the fashion of Saccharomyces (p. 288), 

 and like it induce active alcoholic fermentation. 



Parasites on Mucor. In studying dung-cultures of Mucor 

 Mucedo, it is well to note that it is commonly accompanied by 

 one, or two, other Mucorineae, Chcetocladium Jonesii, and perhaps 

 Piptocephalis Freseniana, which grow parasitically upon it. The 

 mycelial threads of Chcetocladium unite with the mycelial threads 

 and gonidiophores of Mucor, by means of the resorption, at the place 

 of union, of the separating walls. Numerous further prominences 

 arise, and unite with the Mucor hypha as a suctorial apparatus, 

 or haustoria. The mycelial threads of Piptocephalis, on the 

 other hand, cling to the Mucor threads by swollen ends, from 

 which numerous delicate processes penetrate into its interior. 



