GROUP I. THALLOPHYTA : FUNGI. 277 



The archicarp may consist (like the procarp of the Rhodophycese) 

 of two parts ; a receptive portion, the trichogyne, which is a more 

 or less elongated multicellular filament, and a sporogenous portion, 

 the ascogonium, from which, after fertilisation has taken place, the 

 one or more sporangia (asci) of the ascocarp are developed. 



Sexual cells are only clearly differentiated in the case of the 

 female cells of the Oomycetes, and of the male cells of those 

 Ascomycetes in which the sexual organs are not contiguous. The 

 female cells of the Oomycetes are oospheres, spherical cells destitute 

 of a proper wall. The male cells of the Ascomycetes in question 

 are spermatia, small rounded or rod-shaped cells, with a cell-wall 

 and without cilia. It must, however, be mentioned that consider- 

 able doubt exists as to the sexual nature of the spermatia ; and, 

 inasmuch as they have in many cases been found capable of germi- 

 nation, giving rise to a mycelium, there is evidence in favour of 

 the view that they are merely asexual cells of the nature of 

 gonidia (see p. 297). 



In all other cases the protoplasmic contents of 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 Peronosporaceae which enters the oogoriium 

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



A formation of planogametes has been observed in a doubtful Chytridiaceous 

 form Tetrachytrium triceps ; and of spermatozoids with a single cilium in 

 Monoblepharis spliarica a form allied to the Peronosporaceae ; but these observa- 

 tions require confirmation. 



An asexual formation of spores is of general occurrence. Where 

 the life-history is such as to indicate an alternation of generations, 

 these cells may be distinguished as gonidia and spores ; it is, in 

 fact, in the gametophyte that the greater variety and complexity 

 of the asexual reproductive organs obtains. 



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 gametophyte of the higher Fungi, the gonidia are formed, 

 speaking generally, either in the interior of unilocular gonidangia 

 (e.g. most Phycomycetes), or by abstriction, either singly or a 



