MUCORINI. 



237 



the sporangium-wall are absorbed, producing fissures of va- 

 rious kinds e.g., at the base in Pilobolus ; about the middle 

 in Circinella ; irregular in Mucor, etc. The spores germi- 

 nate readily when 011 or in a substance capable of nourishing 

 them (but not in pure water) ; they send out one or two hy- 

 phae (sometimes one from each end), which soon branch and 

 give rise to a mycelium. Spores may, if kept dry, retain 

 their vitality for months. 



318. A second kind of asexual formation of spores takes 

 place in some, if not all, the genera of the Mncorini. The 



Fig. 160. Conjugation of Muwr stolonifer. a, two hyphse near each other, and 

 sending out short lateral processes or branches, which come in contact ; b, the 

 branches grown larger ; c, the formation of a partition near the end of >ach branch ; 

 d, absorption of the wall between the two branches, and the consequent union of 

 the protoplasm of the end cells; e, zygospore fully formed, e X 90; the others 

 nearly the same. After De Bary. 



protoplasm in certain parts of the hyphse condenses and be- 

 comes transformed into single reproductive bodies, known as 

 chlamydospores. Occasionally they form at the ends of 

 hyphae, and are then apt to be mistaken for the " fruiting " 

 of other fungi. 



319. Sexual reproduction takes place after the produc- 

 tion of asexual spores ; the mycelium produces at particular 

 points, in the air or within the nutritive medium, two simi- 

 lar branches, which come in contact with each other, and by 

 fusing their contents give rise to a zygospore (Fig. 160). 



