OERSTED^ ON THE AGARICINI. 25 



Peronospora and Saprolegnia) ; in the flowering plants, 

 indeed, fertilisation has been observed in only a compara- 

 tively small number of species, and yet it will not be doubted 

 that this takes place in all plants furnished with stamens and 

 pistils. 



If, then, wc come to inquire as to the operation of the 

 fertilisation, and as to the relation of the organs of fertilisa- 

 tion to the receptacle, I have not yet succeeded in obtaining 

 so clear a view of this stage of development as to be able to 

 repeat it by a figure ; but, after what I have seen, it must be 

 assumed that the operation of the fertilisation consists in 

 there being thereby called forth a peculiar groAvth of the 

 mycelium filaments bearing the oogonia, so that there be- 

 comes produced a dense tissue proceeding from them, in- 

 cluding several oogonia, which, when it has attained a certain 

 size, presents itself as a little white felted spot, hardly 

 evident to the naked eye — the above-mentioned first rudi- 

 ments of the receptacle. The oogonia after fertilisation do 

 not appear to undergo any further transformation ; only once 

 was seen a beaklike elongation of the anterior part of the 

 oogonium. The fertilisation thus appears to stand in the 

 same relation to the formation of the receptacle as that which 

 (resulting from de Bary's researches) must be assumed to 

 take place in Peziza.* 



To sum up, in conclusion, the results to which the fore- 

 going observations in the development of Agaricus variabilis 

 have led, are as follow : 



1. The mycelium of this Fungus is formed of long dicho- 

 tomously branched tubular cells, without septa, united into a 

 loose web, and with so thin and soft a membrane that it has 

 almost quite the character of a mucous membrane. 



2. From the mycelium cells proceed both vegetative organs 

 of propagation or bud-cells and organs of fructification. 



o. The organs formed as bud-cells have been previously 

 described as and independent species amongst Hyphomycetes 

 [Cephalosporium macrocarpmni). 



4. The female organ of fructification is a reniform oogo- 

 nium, which is curved down against the mycelium-filament, 

 Avhence it originates, with its apex pressed towards it. The 

 male organ of fructification consists of two filiform antheridial 

 cells proceeding from the base of the oogonium. 



5. After fertilisation several oogonia in union give rise to 

 the formation of a receptacle. The oogonia are included in 



* ' XJeber die Fruchtentwickelung der Ascomyceten,' von Dr. A. de Bary, 

 1863. 



