THK CKLL .MKMIiHAXE. 147 



ascertiiiuLMl \>y Mii.kku (IV.), and afterwards by C, VOK 

 WlKSELiN'tiU (1.) Tliu aljsence of any aiJitieciiihle action of 

 ammoniac-al copjiei- oxido on tlie yejist cell had ahoady been 

 obseivfd )»y LieMj;. According' to tlit' cont-ordant results fur- 

 nished \>\ the researches undertaken by C. vox WissELlxuil and 

 by Tamiet (111.), chitin, the second material taking part in 

 the structure of tiie cell nienilirane uf the Kuiiii/rrftjs in genenil, 

 also .seems to be lacking in the ca.•^e of yeastK The alleged 

 observation, by Clutis(I.), c»f a violet colouration |»r(j<luced by 

 zinc iodochloiide on the mendiraiie of a pathogenic budding 

 finigu.s, was ih'dared by L'asjigrandi to In- erioneous ; .md no 

 more than a faint yellow colouiation is jir<Kluced in the meujlmine 

 of vegetative yea.st cells by simple iodine .soluti<jn. According to 

 H. W'iM. (IX.), the report maile by .several observers to the 

 elVect that the spoie membrane of v.irious yea.sts is strongly 

 tin''ed a vtdlowish brown bv zinc iodociiloi ide, must be cor- 

 rected in the sen.se that the seat of this c«)loiuation is not in 

 the spore membrane itself, l>ut in an overlying uncousume<l 

 re.sidue of the plasma of the parent-cell. This \N'ill was able t<j 

 determine more particularly in the ca.se of two .species of wild 

 yeast exiimined. According to J..IXUXEK (VII 1.), the s|K)ies of 

 JSrhizn-iSai'i'lniruiiii/reji urfusjiurii.'! exhibit a very peculi.ir behaviour 

 in this respect, a powerful l»lue colouration being impaiti-d l>y 

 iodine and potassium iodide to the spore memVirane, and often 

 to that of the vegeL;itive cells as well. The .s;ime behaviour was 

 observed by ,). Ch. Holm in another species allied to the one 

 just mentioned. Along with the.se exceptions must also 1)6 

 cla.s.sed the blue colounition ob.served by Likhei{M.\xx and BiTTo 

 (I.) oji the addition of zinc iodochloride U) a macroscopical pre- 

 paration of .so-called yeast cellulose (;< 225). In connection 

 with this behaviour of the yeiv.st cell menibmne towanls colour- 

 ing matters, (_'a.s;igrandi remarks tlmt Congo Red is not ab.sorl)ed, 

 whereas, on the other hand, very good staining can be elTecttnl 

 with Ehrlich's Methylene Blue or ll.instein's Aniline Violet. 

 C Beckeu (I.), however, found only the latter of these two 

 etTective. Solution of the mi'inbrane (M-curs on the cells being 

 immer.sed in concentrated chromic or sulphuric acid, whilst other 

 acids are inetfei'tual. The s;ime applies to the mixture of nitric 

 acid and potissium chlorate, known as iSchulzes macer.itiou 

 liipiid. through its mode of action having fir.st been ob.served 

 and utilised bv Hrunnengi;eber in the l.iboi-.itorv of Profe.s,sor 

 F. F. Schulze at Ho.stock. This is related l)y A. T.siiniKii (IV.) 

 in an admirable historical review of microchemical methods. 



The foregoing, together with a series of other microchemical 

 reactions, led Ca.sjigrandi to the belief that the yej»-'>t cell mem- 

 brane contains a substnnce chemically .-illied to the pi*ctin 

 recognised by Mangin as a constituent of other vegetable mem- 

 branes. It is, however, dillicult to a.scertain whether and how 



