ZYGOMYCETES 



689 



duction appears to be wanting among the higher fungi (excepting 

 perhaps some of the Ascomycetes), only asexual propagation being 

 known with certainty. 



PHYCOMYCETES. 



Sub-class i. Zygomycetes. 



In the Zygomycetes, conjugation (a fertilisation-process be- 

 tween two similar branches of the mycelium) takes place, 

 and results in the formation of a thick-walled resting-spore 

 termed a zygospore. 



Asexual reproduction is carried on by means of non-motile 

 endospores which arise within sporangia occurring at the ends 

 of erect hyphse {s, Fig. 230), and in some species by means of 

 conidia also. 



A small number of fungi belonging to this sub-class of the 

 Phycomycetes are parasitic 

 upon plants and insects, the 

 greater portion of the Zygo- 

 mycetes, however, are sapro- 

 phytes. One of the common- 

 est species, namely Mucor 

 Mucedo L., occurs as a 'mould' 

 in all parts of the world upon 

 damp bread, jam, and other 

 organic substances, especially 

 those containing starch and 

 sugar. Its mycelium ramifies 

 in all directions through the 

 substratum on which the 

 fungus feeds and grows, and 



. . . Fig. 230. — « Sporangiophore of j^wc(wiJ/M«^£7 



from it are sent up mtO the L. at the apex of which is a sporangium W with 



. endospores ; b free endospores ; ct and cl^ two 



air numbers 01 erect, trans- successive stages of germinating endospores ; h 



, , , . . . 1 • hypha (enlarged 300 diameters). 



parent hypha, bearing at their 



tips single spherical sporangia in which are numbers of oval 



spores (Fig. 230). 



