("HITIN. 



37 



series of isomeric or nearly allied substances, aiul therefore of 

 the necessity of rej.'anlin'; the name cliitin as a collective ttMm. 



The extent to which chitin is jiresent in <lill"i?rent j^roups of 

 fun},'i WHS investi^Mted by C van Wisselixgu (I.) in n-seaidjes 

 already leferred to in j>revious jiaraf^raiths. Its absence was 

 confirmed by this worker in the case of liaderia, Ounn/cetejt 

 {S(tprule<jnietf and l'eronospoi'e(v) and >Sac''Jian/iiii/relen examined 

 by him. In all the other species of finifji examined, however 

 (about a liundred), the presence of chilin was invariably detected, 

 e.'j. in MuL'ur muceilo, M. rucemosm*, Rhizoinu* nii/rirann, Penicil- 

 h'utn ij/itnruiii, Tn'rothecinm rosruin, in the sclerotia of fiutnjtis 

 rini'rea and C/arire/ix jntrjiurra, itc. At j)resent no inst;ince of 

 the simidtuneous occurrence of cellulose and chitiu in the cell 

 membi-ane of a funjrus is known. In many cji-ses, e.if. the 

 jterithecial wall and the a.sci of A/i/xri/il/iin i/luui-if^, the membrane 

 is partly conj[)osed of other substjinces. With the assistance of 

 im})roved microchemical tests \Vi.sselin;,'h has also studie<l the 

 l(K'al di.'<tribution of chitin in the cell membrane, and has found, 

 for instjince in the wall of the ascospores of J, -y //////«.< ijlawHS, 

 that chitin is [present in the form of two kinds of biconvex 

 jdates. 



For iutoiiuation respecting; the amount of chitin present in 

 certiiin funjLji we are indebted to C. Tanuet (III.), accordinr; to 

 wliose determinations — which, however, must be regarded as 

 merely approximate e.stimates — about 15 per cent, of this sub- 

 stiince is found in AsjU'riiiUun nvjer. 



^ 227.— Hemicelluloses and other Carbohydrates. 



Of the two main •.'roups uf carbohydraies <.ii the formula 

 C",.H,„Oj entering into the composition of cell memluanes. the 

 occurrence of true cellulo.se in fungi hius been tlealt with in 

 J$ 225, and there remain theiefore only the representatives of 

 the secoml group, namely, the hemicelitiloses (.^ iiS) and other 

 eji.sily hydrolysed carbohydrates. Apart from the rejK)rt 

 furnished by UitACOX.NET (I.), we are indebted to the French 

 chemi.«<t Ciiamimono.v (I.) for the earliest ob.servation of these 

 substances. From a subterranean fungus. Par/,,/„ia Ccruis Fri'g, 

 largely consumed in China under the names Fid>-ling. Fouh- 

 ling. and Pe-fuh ling, this worker i.solated a carluihydnite of the 

 formula ^^'ooH^s^.j^' which, on being treated with dilute acid, is 

 converted into a licjuid capable of nvlucing Fehling's .solution. 

 To this carbohydrate^ he gave the name pachyman. l-'iter, 

 E. WlXTEUSTElN (II.). isolate.l from the edible boletus (/h<A/?/jJ 

 ediih'ii) a carbohytlrate which is soluble in dilute acids and 

 re-i>it'cipitated by alcolud. This substance 1ms re*^'eive<I the 

 name paradextran, and its elementary formula is C,.H,,,0,. 

 Closely allitd tluM.-to. .uid of the sjune composition, is paraiso- 



