58 FUNGI. 



The hymenium is, however, the most important part, con- 

 sisting of (1) the paraphyses, (2) the asci, and sometimes (3) 

 an investing mucilage. The asci are always present, the para- 

 physes are sometimes rare, and the mucilage in many cases 

 seems to be entirely wanting. 



The paraphyses, which are formed at the first commencement 

 of the receptacle, are at first very short, but soon elongate, and 

 become wholly developed before the appearance of the asci. 

 They are linear, sometimes branched and sometimes simple, 

 often more or less thickened at their tips ; almost always they 

 contain within them some oleaginous granules, either coloured or 

 colourless. Their special function seems still somewhat obscure, 

 and Boudier suggests that they may be excitatory organs for 

 the dehiscence of the asci. However this may be, some mycolo- 

 gists are of opinion that, at least in some of the Ascomycetes, 

 the paraphyses are abortive asci, or, at any rate, that abortive 

 asci mixed with the paraphyses cannot be distinguished from 

 them. 



The mucilage forms itself almost at the same time as the 

 paraphyses, and previous to the formation of the asci. This 

 substance appears as a colourless or yellowish mucilage, which 

 envelopes the paraphyses and asci, and so covers the hymeiiium 

 with a shining coat. 



The asci appear first at the base of the paraphyses, under the 

 form of oblong cells, filled with colourless protoplasm. By rapid 

 growth, they soon attain a considerable size and fulness, the 

 protoplasm being gradually absorbed by the sporidia, the first 

 indication of which is always the central nucleus. The mucilage 

 also partly disappears, and the asci, attaining their maturity, 

 become quite distinct, each enclosing its sporidia. But before 

 they take their complete growth they detach themselves from 

 the subhymenial tissue, and being attenuated towards their base, 

 are forced upwards by pressure of the younger asci, to, and in 

 some instances beyond, the upper surface of the disc. This 

 phenomenon commences during the night, and continues during 

 the night and all the morning. It attains its height at mid- day, 

 and it is then that the slightest breath of air, the slightest 



