32 THE CELL MEMBRANE OF EUMYCETES. 



named reagent, Feemy (I.) showed that, in many cases {e.g. 

 mushrooms), it is incapable of dissolving the cell membrane of 

 fungi, and, consequently that the membrane is constructed, not 

 of pure cellulose but of a substance (of unknown constitution) 

 to which he gave the name metacellulose. A similar opinion on 

 this point was pronounced by A. DE Bary (III.), who gave ex- 

 pression to his views by employing the name fungus-cellulose 

 for the substance in question. In this connection mention 

 should also be made of Mulder's observations on the behaviour 

 of the membrane of yeast towards iodosulphuric acid. More 

 complete particulars with regard to this class of cell membrane 

 will be found in § 249. 



Very soon, however, doubt began to arise as to whether any 

 special or peculiar character was really possessed by the so- 

 called fungus cellulose. As far back as 1858 it was shown, by 

 Carl Cramer (I.), that the solvent action of Schweizer's reagent 

 on true cellulose was retarded, or even entirely prevented, by 

 the presence of foreign incrustations in the membrane. Opinion 

 then showed a tendency to favour the idea that the membrane 

 of fungus cells contains a fundamental substance like cellulose 

 — and to which Tschirch (III.) gave the name mycin — , but 

 that this could not be detected by the aforesaid reagents owing 

 to the presence of interspersed incrustations. This view was 

 specially championed by K. Richter (I ). By his investigations 

 on a series of fungi — including Becale cornutum, Agarirus cam- 

 2>esfris, and others wherein A. de Bary had observed the 

 assumed fungus cellulose — this worker, in 1881, proved that 

 when such membranes did not immediately give the reactions 

 in question (especially with iodine), they could be induced to do 

 so by steeping them for not less than a fortnight in a 7 /to 8 

 per cent, solution of caustic potash. The elementary composition 

 of the membrane so treated, he found to correspond to the 

 formula 7^{C^'H.y^^0r). 



Even this observation did not remain unopposed, the same 

 hypothesis being urged against it that every investigation into 

 the nature of the cell membrane has had to contend with ever 

 since the days of Pay en, namely, the question whether this 

 preliminary treatment of the membrane merely results in the ex- 

 traction of the extraneous admixtures, or whether it is not rather 

 that the fungus cellulose is converted into true cellulose. How- 

 ever, even apart from this doubt — which will be further con- 

 sidered in subsequent paragraphs — Richter's observations do not 

 disprove the assumption that a substance, differing from pure 

 cellulose, occurs in the membrane of fungi, since, in some of his 

 experiments, the cellulose reaction could not be observed in the 

 preparations employed. Nevertheless, although, in view of the 

 last-named circumstance, it cannot be admitted that, strictly 

 speaking, Richter's experiments actually identified fungus cellu- 



