286 



PART IV. CLASSIFICATION. 



gametangia are absorbed at the point of contact ; the protoplasmic con- 

 tents (gametes) of the gametangia fuse to form the cell which surrounds 

 itself with a coat of two layers and becomes a zygospore (Fig. 166). 



In many cases the zygospore, on germination, gives rise to a small 

 branched or unbranched mycelium, which bears a single simple sporo- 



phore. The spores 

 derived from this 

 sporophore give 

 rise, on germina- 

 tion, to the ordin- 

 ary mycelium. In 

 other cases, how- 

 ever, the zygo- 

 spore gives rise 

 directly to a my- 

 celium bearing 

 sexual organs. 



The mycelium, 

 when under un- 

 favourable con- 

 ditions, gives rise 

 to unicellular 

 gemmae, either 

 c h 1 a m y d ospores 

 or oidium - cells : 

 the latter multi- 

 ply by gemmation 

 in a yeast -like 

 manner (e.g. Mu- 

 cor racemosus) and, 

 like Yeast, have 

 the power of caus- 

 ing alcoholic fer- 

 mentation ; this 

 takes -place espe- 

 cially when the 

 hyphse are im- 

 mersed in liquid. 

 The hyphse be- 

 come segmented 

 into a row of cells 

 by the formation 

 of transverse 

 septa, and the 

 cells then sepa- 

 rate and become 

 free. The chla- 

 mydospores are 



FIG. 166 Mucor Mucedo: A diagram of sexual process: two 

 gametophores in contact ; at the end of each gametophore a cell, 

 the gametangium, has been cut off by a septum ; B commencing 

 development of the zygospore from the fused gametangia; C ripe 

 eygospore, still connected with the gametophores; D free zygo- 

 spore, showing one point of attachment ; E germinating zygo- 

 spore, bearing a small ,'promycelium with a single sporangium 

 (after Brefeld). 



