236 Dr. A. de Bary on the Mycetozoa. 



knowledge of the Fungi is insufficient for the construction of a 

 natural classification to replace the artificial one alluded to. 



The two groups or orders of Fungi more immediately falling 

 under notice in this memoir are : 



1. Ascomycetes, having dilated saccular sporothecse (asci), 

 wherein the spores originate by the free genesis of cells : e. g. 

 Tuberacei (Truffles), Pyrenomycetes and Discomycetes, to which 

 the Lichens are most nearly allied. 



2. Basidiospori, producing spores from parent-cells (basidia). 

 The free extremity of the basidium produces offshoots which 

 acquire the form and dimensions of spores, and drop off, after 

 the development of a dissepiment. Mostly four spores are formed 

 and detached from a basidium simultaneously : one, two, or six 

 are rarely produced. The basidia are congregated together 

 in large numbers as spore-strata, or hymenia, lying parallel 

 one above another and at right angles to the fibres from which 

 they spring. 



The Basidiospori form two principal sections: 1. Hymeno- 

 mycetes, in which the whole of the hymenium, or only certain 

 definite portions of it, occupies the free surface of the Fungus, 

 as, for example, in Agaricus, Hydnum, Boletus, Polyporus, Cla- 

 varia. 2. Gasteromycetes, in which the hymenium is lodged 

 within a definite cavity (the peridium) in the substance of the 

 Fungus, which opens when the spores are ripe, to permit their 

 escape: to this division belong Lycoperdon, Bovista, Geaster, 

 Cyathus, and many others belonging to the groups Hymeno- 

 gastrei, Nidulariacei, and Lycoperdacei. 



In many Gasteromycetes (such as Ly coper don, Bovista, Geas- 

 ter) having large peridia., these cavities contain, when ripe, the 

 powdery spores mixed with more or less dry furfuraceous matter, 

 and a hair- like mass, the <e capillitiurn " (fig. 3). The peridium 

 itself is, when in the same mature condition, a dry membrane of 

 variable thickness, and sometimes divisible into several laminae. 



When, however, the spores are in course of development, 

 these Fungi are fleshy, spongy, and imbued with much mois- 

 ture : the cavity of the peridium is at the same time perceived 

 to be divided into countless microscopic cells, separated by 

 lamellae from the anastomosing cavities of the network of the 

 surrounding tissue. The inner wall of each cell or chamber is 

 covered by a layer of spore-bearing basidia. The spores soon 

 detach themselves from their supporting basidia, which, together 

 with a portion of the tissue upon which they rest, become, 

 during the ripening of the spores, dissolved and absorbed. 

 During these changes, the fibres of the lamellse> after the evapo- 

 ration of the watery contents, become dry and produce the 

 capillitium of the mature Fungus. Thus all the various struc- 



