68o FUNGI : GENERAL 



thread-like. In many instances the spore possesses a double 

 cell-wall; the outer membrane, termed the epispore, is often thick 

 and ornamented, while the inner one is usually transparent and 

 thin. In regard to their mode of origin two types of spores 

 are recognisable, namely : — 



(i) Those which are the result of a fertilisation-process, or 

 sexually produced spores ; and 



(ii) those which originate asexually. 



The latter are most prevalent among all kinds of fungi, 

 and only in the lowest forms or the Phycomycetes (p. 686) are 

 sexually-produced spores met with, unless the spores of some 

 Ascomycetes belong to this group. One form of sexually- 

 produced spore originating after a conjugation process is termed 

 a zygospore (p. 686), and is characteristic of one sub<lass of 

 the lower fungi; the other, typical of the second sub-class of 

 the Phycomycetes, is known as an oospore (s, Fig. 233), and is 

 described on page 692. 



Of asexually-produced spores three types may be recognised, 

 namely : — 



(i) Endospores, 



(ii) Conidia, 



(iii) Oidia and chlamydospores. 



(i) Endospores are spores which arise by division of the 

 protoplasm within a mother-cell ; the wall of the latter acts as 

 a case for the spores and is termed a sporangium, the special 

 hypha at the end of which the sporanguim is borne being 

 designated a sporangiophore. 



The endospores of some of the lower fungi are naked pieces 

 of protoplasm furnished with vibratile cilia which enable them 

 to swim freely in water as soon as tliey are liberated by the 

 rupture of the sporangium {s. Fig. 230) ; such motile spores are 

 termed zoospores or swarmspores. Most endospores, however, 

 are non-motile cells with a distinct cell-wall (Fig. 230). 



Sporangia are chiefly spherical or oval in form, though they 



