GROUP I. THALLOPHYTA : FUNGI. 279 



spherical cells destitute of a proper wall : the spermatia generally 

 have a cell- wall. 



In all other cases the protoplasmic contents jof the sexual organs 

 are not differentiated into cells of definite form ; but the fusing 

 masses of protoplasm of the Zygomycetes may be regarded as 

 aplanogametes ; and that portion of the protoplasmic contents of 

 the pollinodium of the Peronosporacese which enters the oogonium 

 and fertilises the oosphere, may be regarded as a male cell. 



An asexual formation of spores is of general occurrence. In the 

 Schizomycetes there are no special spore-bearing organs, but the 

 protoplasm of the cells surrounds itself with a proper cell-wall, and 

 becomes a spore. 



In the Myxomycetes sporangia are formed, attaining, in some 

 forms, a high degree of complexity of structure. 



In the higher Fungi, the spores are formed, speaking generally, 

 either in the interior of unilocular sporangia (e.g. Phycomycetes), 

 or by abstriction, either singly or a number in succession, from 

 certain special hyphse (as in the Ascomycetes, JScidiomycetes, and 

 Basidiomycetes) ; in the latter case the spores are often distin- 

 guished as conidia. 



In either case, the spores are borne upon an organ, a special 

 branch of the mycelium, termed a sporophore or conidiophore. 

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

 Penicillium, Puccinia), when it is said to be simple ; or of a 

 number of coherent hyphse (e.g. the Mushroom, and the fructifica- 

 tions of other Basidiomycetes ; the ascocarp of the Ascomycetes ; 

 the secidium of the ^Ecidiomycetes) when it is said to be com- 

 pound. The conidiophores may be scattered over the mycelium, 

 or they may be collected into receptacles termed pycnidia. 



The asexually-formed spores are but rarely motile (e.g. ciliated 

 zoospores of Myxomycetes 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 are compound ; 

 that is, they appear to consist of two or more cells (e.g. teleuto- 

 spores of Puccinia Graminis and other vEcidiomycetes ; ascospores 

 of some Ascomycetes such as Pleospora, Hysterium, Cordyceps, 

 etc.) ; each cell, however, germinates independently and is there- 

 fore itself a spore. These compound spores are formed by the 

 division of a primary mother-cell. 



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

 cated by . polymorphism. In most of the Schizomycetes there is 



