TJIK CA1M;()11VJ)KATK (JJiOrP. ,;9 



Tho a.Mitioii of a lai-u,. .juaiititv of water to the ywu,t 

 -ll-ssolvt-s the network. NeVLMtheless/as HaiiHeii has Kh.mn, it 

 tonus anew, unles.s the treatiinMit be repeated suflicieiitlv often 

 •md prolonj^'cl. Acvonlin^r Uj II. Wm.l (VII.), lioweve'r, it is 

 pernuiiu-ntly remove.! wh.-ii tl»e wa.shii.g is repeated t<?n times 

 m twenty-four liours N„w, since the percenUi<:e of the con- 

 stituents forming the network in l^eer ve^ist (and also prfs.sed 

 yea.st) inHuences the compressibility of tlie mass, it follows tlmt 

 this proj.erty may un.ler ci-rtiin circumst^inces Ik? impaire<l by 

 the metluxl pursued f..r washinjj the yeast (§255). On the 

 other hand, it ibeeomes indispcn.siible to' remove these mucinous 

 constituents from the yeast when the latter has to be subjec-Wd 

 to a .juaiitifative macrix-heniical analvsis for the purfKise of 

 a.scertiining the composition ..f the corpus of the cell. This 

 purification might be efTecte.l by the washing proce.ss, were it 



1/ 





FlO. 158. — KragmenUo( Gelatinous .Network. 

 KrimiabeeryeaaL InstaineiL Magn. looa. (After Uaiitnis vri.jinal drntring.) 



not that the treatment .so far modifies the cells themselves as to 

 make the results of the analysis, under cei-tain circumstances, 

 not worth the trouble e.xpended thereon. 



In this case also, pi-.ictic^il use may be made of the general 

 property of the vegetiiblo gums for thickening to a jelly in 

 presence of bora.x st)lution, and thus separating from the liquiil. 

 On the ba.sis of .m observation by Dimas (III.), II. Will (I.) 

 found that a thick barm of beer yea.st, when treated with a 5 per 

 cent, .solution of bora.x, immediately agglomemtes into pure 

 white lumps, which (piickly subside and unite into large .solid 

 niasses that fairly crackle when spread out on plates of gvpsum. 

 This behaviour is advantageously utilised in the pnxluction of 

 pure-culture yeast on a practical .scale. The thick barm of vesust 

 from the fermenting cylinder of the ])ure yeast appar.it'us is 

 u-eated with a similar solution of Inmix, wlien destined to be 

 sent out in a pressed state. This treatment not only accelerates 

 tlie deposition of the yeast and consi.lenibly facilitates pres.sing. 

 but also greatly ameliorates the colovu- of the yeast, ai»d there- 

 fore improves its appearace, without imi«uring the fermentative 

 power to any appreciable extent. It would therefore seem that 



