FUMGI. 83 



hyphae of the mycelium has been several times observed, especially in plants 

 cultivated in artificial solutions; the cell-walls are absorbed at the points where 

 two filaments touch one another, and the filaments thus communicate with one 

 another. This proceeding is obviously distinct from the phenomena of sexual 

 reproduction observed in the conjugation of the Zygomycetes. 



It is through the gonidia that Fungi are most abundantly reproduced. These 

 are either non-motile cells, or zoogonidia (swarm-spores) ; the latter are found 

 in Fungi that live in water. Both kinds of gonidia may occur in nearly allied 

 plants. Pythiinn, for instance, has zoogonidia, the rest of the Peronosporeae non- 

 motile gonidia. The non-motile cells are the result of abjunction, or of the divi>ion 

 of the contents of a mother-cell that has swollen into a spherical form. The most 

 prevailing mode of formation is abjunction ; examples are seen in Cysiopus (Fig. 

 56, B), in the Basidiomycetes (Fig. 90), and in the Uredineae (Fig. 85), where cases 

 of the formation of gonidia by abjunction are represented. In all of them the 

 end of the mother-cell or the process or protuberance formed on it is abjointed 

 from it by a parting wall as a daughter-cell, which developes into a gonidium 

 and finally drops off. The process is repeated in Cysiopus ; when one gonidium 

 has been formed another is formed beneath it, and in this way gonidia-chains 

 are produced on the summit of the mother-cell, which is called a basidiu/n, in 

 the wider sense of the term. The aecidiospores of the Uredineae (Fig. 85), the 

 gonidia of Penicilliimi, Erysiphe (Fig. 65) and others are formed in the same way. 

 The gonidia of the Basidiomycetes are formed on the swollen club-shaped terminal 

 cells of branches of the hyphae. These cells are termed basidia in the more 

 restricted sense and put out narrow pointed processes, sterigmata (Fig. 90, E), the 

 extremity ot which swells into a ball and enlarges, and is then abjointed as a go- 

 nidium. When this is done the basidium disappears, for in this case there is 

 no repetition of the process of formation and abjunction. The gonidia of the 

 Uredineae (the iiredosporcs and the tdciitospores) are formed by the delimitation by a 

 transverse septum of the upper portion of a cylindric somewhat club-shaped 

 mother-cell (Fig. 85, // and ///), the mother-cell serving as a stalk to the 

 gonidium which does not drop oft" of its own accord. Lastly, the gonidia of 

 Miicor are minute cells produced in large numbers inside hemispherical stalked 

 sporangia, and are set free by the dissolution of the wall of the sporangium. 

 The cells forming gonidia are either free and isolated, as in the last-mentioned case, 

 or they form either by themselves or in combination with sterile hyphae an aggregate 

 of cells which is termed the hymenium, a name usually applied to a layer of hyjihae 

 bearing propagative cells, whether asexually or sexually produced. The sexual 

 mode of formation of spores, so far as it presents any peculiarity, will be described 

 below. 



Systematic arrangement of the Fungi'. The Fungi include a number of 

 foims, in which the course of development resembles that of Vaiicheria, Oedogonium, 

 and other genera of the Chlorophyceae ; the germinating spore, whether zygospore 

 or oospore, produces a thallus consisting of free hyphae not interwoven with one 



1 De Bary, Grundlagen e. Natiirl. Systems d. Pilze in Beilr. zur Morphol. 11. Thysiol. d. Pilze 

 von De Bary u. Woronin, IV. Reihe, p. 107. [Also De Bary, Vergl. Morph. u. Biol. d. Pilze etc., 

 Leipzig 1884.] 



