1899] MICROSCPOICAL JOURNAL. 149 



Mucorini. A pot of jam or paste is thickly studded with 

 apparently very long slender pins, each with a small 

 round head. This is Mucor mucedo. The round head is 

 found to be a sporangium or capsule filled with spores, 

 which readily germinate in a suitable medium, and give 

 rise to an abundant mycelium which again produces the 

 sporangia in a very short space of time but under cir- 

 tain circumstances we may find a very different form of 

 reproduction, similar to what is found in many algae, and 

 called zygospores. They originate thus : two neighbor- 

 ing branches of the hyphae approach each other tip to tip, 

 become swollen or club-shaped ; a septum is formed cut- 

 ting off the terminal portion of each. The portion so 

 cut off is called a gamete. The two gametes are at first 

 separated by their respective cell-walls, these soon disap- 

 pear and one large cell is left suspended from the two or- 

 iginal branches. The wall quickly thickens and assumes 

 variously warted or spiny appearance extei'nally and has 

 the property of retaining its power of germination for a 

 long time. Through the genera Pythium and Saproleg- 

 nia already referred to the Mucorini approach more or 

 less closely the PeronosporesB. 



Space will admit of notice of but two more sections of 

 microscopic fungi — the Phacidiacei and the Sphaeriacei. 

 Both these occur in general on dead leaves, stems, or 

 wood, while a few are parasitic on living plants, on 

 grasses or living insects, which latter, however, they ul- 

 timately kill. All have spores borne in asci and con- 

 tained in perithecia or receptacles very like those in the 

 Perisporiacei. 



In the Phacidiacei the perithecium opens by valvular 

 teeth, in the Sphaeriacei by a central pore; of the for- 

 mer a familiar instance may be found in the Rhytisma 

 acerinum which forms black patches so common on syca- 

 more leaves, the fruit being perfected in spring, as the 

 leaves lie decaying on the ground. Other, such as Stegia 



