40 THE CELL MEMBRANE OF EUMYCETES. 



hand, the lignin reaction (with sulphuric aniline sulphate) was 

 furnished by the large pileated fungi, though whether the pre- 

 sence of lignin is thereby proved must remain an open question. 



Not infrequently a deposition of colouring matter is found 

 in the cell membrane, usually in such a condition as to be incap- 

 able of extraction by any known solvent ; this is the case with 

 the conidia of AspergiUns and Penicillium. In other coloured 

 fungi the colouring matter is embedded in the plasma ; of this a 

 fine and technically important example has already been given 

 in § 219. 



Whether the waterproof character of some cell membranes, 

 e.fi. in the conidia of Penirillivvi and AfpergtUus, should be attri- 

 buted to the deposition of excreted fatty or waxy substances, 

 must be left undetermined. Biologically this phenomenon is 

 important since it prevents the penetration of toxic substances 

 from the surrounding aqueous medium, and thereby also opposes 

 the attempts of the mycologist to kill such fungi by means of 

 aqueous toxic solutions. 



Deposits and incrustations of calcium oxalate crystals are of 

 very frequent occurrence in the membrane of fungi, especially 

 on the surface of the spores. In many cases their presence and 

 appearance afford characteristic indications valuable for the 

 jiurposes of classification. 



