ii4 INTRODUCTION TO THE STUDY OF FUNGI 



sporangia being asci-like; and (2) the Hemibasidia, which 

 connect the -basidia -bearing forms with the simpler Zygomy- 

 cetes. The former of these, the Hemiasci, consist of three 

 families: (1) the Ascoideae; (2) Protomyceteae ; and (3) 

 Theleboleae. In these simple forms the sporangium becomes 

 like an ascus, but indeterminate in size or form or the number 

 of spores, and these latter are usually shot out with consider- 

 able force. The Hemibasidia fructify by gonidia without 

 sporangia, but the gonidiophores partake of the character of 

 basidia. This group includes the Ustilagineae and the Tilletiae. 

 According to the views of this author all the higher Fungi had 

 their origin in Zygomycetes, and the two series of Basidio- 

 mycetes and Ascomycetes were developed in different directions, 

 the former excluding sporangia, and developing specialised 

 gonidiophores or basidia, while the latter retained indefinite 

 gonidiophores, but developed those special sporangia which are 

 known as asci. 



This brings us to the Mycomycetes, which, as already 

 stated, consist of two series : (1) the Ascomycetes, where the 

 fructification is by definite sporangia (asci) and conidia ; and 

 (2) Basidiomycetes, in which the fructification is by gonidia 

 without sporangia, and the gonidiophores are determinate 

 (basidia). Ascomycetes are characterised by the presence of 

 the ascus, which is a sporangium of determinate form, and the 

 number of its spores. In many cases this form of fructifica- 

 tion is accompanied by gonidia and chlamydospores. When 

 mature the spores are often forcibly expelled. Sexual organs 

 do not occur, since the earlier observations ascribing sexuality 

 have been found to consist of misinterpretations. The Asco- 

 mycetes are subdivided into Exoasci and Carpoasci. The 

 Exoasci have naked asci borne directly on the mycelium-. The 

 Carpoasci have fruit-bodies ; the asci are not naked, but are 

 contained in special organs composed of fertile hyphae and 

 sterile threads, which latter form the walls of the envelope. 

 The simplest forms of ascus fruits are angiocarpous, and in the 

 highest of the Pyrenomycetes with a special ostiolum. In the 

 Discomycetes and Hysteriaceae they are gymnocarpous, or 

 closed at first and afterwards open. The Carpoasci have also 

 accessory fruit -forms, and in addition to free gonidia and 



