278 PART III. THE CLASSIFICATION OF PLAKTS. 



number in succession, from certain special hyphse (as in the 

 Ascomycetes, ^Ecidiomycetes, and Basidiomycetes) ; in the latter 

 case the gonidia may be generally designated stylogonidia. 



These stylogonidia has received special names, such as uredospores, teleuto- 

 spores, basidiospores, etc., with the object of indicating the group to which 

 they belong, or peculiarities in their development. These terms (more correctly 

 uredogonidia, teleutogonidia* basidiogonidia) are explained in the descriptions 

 of the various groups. 



In either case, the gonidia are produced at the apex of an organ, 

 a special branch of the mycelium, termed a gonidiophore. This 

 may consist of a single hypha (e.g. Mucor, Peronospora, Penicil- 

 lium, Puccinia), when it is said to be simple or of a number of 

 coherent hyphse (e.g. the Mushroom, and the fructifications of other 

 Basidiomycetes) when it is said to be compound. 



The gonidiophores may be scattered over the mycelium, or they 

 may be collected into receptacles termed pycnidia. 



In the sporpphyte of most Phycomycetes and all Ascomycetes, 

 the spores are always found in the interior of a sporangium 

 (termed, in the Ascomycetes, an ascus}', in the .^Ecidiomycetes 

 they are formed by successive abstriction from basidial cells form- 

 ing part of the secidium. In some cases (e.g. certain Mucorinse and 

 Peronosporaceae) the sporangia are borne on special hypha, which 

 are termed simple sporophores ; and the more complex ascocarps of 

 the Ascomycetes may be regarded as compound sporophores. 



The asexually-formed spores and gonidia are but rarely motile 

 (e.g. ciliated zoos pores and zoogonidiaof Myxomycetes,Chytridiace83, 

 and Oomycetes) ; in all other Fungi they are non-motile and have 

 a cell-wall. There is considerable variety in their form, colour, 

 etc. In some cases the spores or gonidia are compound ; that 

 is, they appear to consist of two or more cells (e.g. teleutogonidia 

 of Puccinia Graminis and other JEcidiomycetes ; ascospores of 

 some Ascomycetes such as Pleospora, Hysterium, Cordyceps, etc.) ; 

 each cell, however, germinates independently and is therefore 

 itself a spore or gonidium. These compound spores and gonidia 

 are formed by the division of a primary mother-cell. 



The Life-History of the Fungi is generally very much complicated 

 by polymorphism. In most of the Schizomycetes, although there 

 is no alternation of generations, there is remarkable polymorphism, 

 especially in the higher forms which pass through several distinct 

 phases in the course of their life. In the sexual forms an alter- 



