THK ('AIII'.OHVDKATE rJUOl'l'. 175 



■^ 254. Mucinous Substances of the Carbohydrate 

 Group. The Gelatinous Network. 



Umlfi- tin- iKtim- \ca>l j.'uui, >f\L'iiil \vuik«*r> have isoliiU'd 

 mucinous carbohydrates from yt-ast. Thou;,;!! Mjuie of tliese 

 products have not been closely t'xuiiiined, they Imve been so fur 

 characterised that we may assume the alx»ve name to be nothing; 

 more than a collective term. They all behave in the sa^ue 

 manner towards Fehlinij's solution, a circumst-mce of some 

 value in connection with their iirepanition and isolation, since 

 all are preci]»itjite<l by this reagent, as a blue, lum]iv co|ij>er 

 compound, from neiilial oi- faintly alkaline solutions. 



On leaving yeast to uiidergo autofermentJition (see a later 

 para<:raph) in water, J. liKCIIAMl' (VIll.) in 1874, discovered in 

 the liquid (whieh was protecte<l from invasion by jiutrefactive 

 organisuhs) a gummy and optically active .substance, the rotjitory 

 power of which he ascertiiined to be +59-6i\ This sub- 

 stiince first receiveil closer attention at the hands of X.ticKLl 

 and LoF.w (II.) in 1S78, who prepared the yeast gum 'or 

 fungoid mucin as they called it) by exti-jicting yea.st with boiling 

 water, freeing the extract from phosphoiic acid and peptone 

 with lead acetiite. removing the exce.ss of lead with sulphuretted 

 hydi-ogeii, and precipitiiting the gum with hot aleohol. Re- 

 peated .solution in water and repreci{)itationwith alcohol furnishetl 

 a white powder, which exhibited a relationship with dextran in 

 many lespects, >.;/. in Vieing precipitable by alkaline i««pper 

 solution, though its rotiitory powei- was much h-.^s. namely 

 + 78°. The formula 3(C^H,„0,,) + 2H.,0 was deduced from the 

 results of ultimate analysis. This gum was gradually convertt-d 

 into glucose by the action of acids; w.is stained brown-red l>y 

 iotline ; and therefore— as Eureka (II.) surmised with gootl 

 rea.son — als<i cont.-iined glycogen. 



Weoxek (I.) cl.is.sed as ilextran the gum he obtained in iSqo 

 from ye.i.st by the Scheibler method de.scribe<l in Jj i6o. In the 

 dry st;ite this is a white amorphous neutnil powder, which is in- 

 soluble in alcohol, and swells up in watt-r to an t>j»ale.scent 

 litpiid, the rotatory jmwer of which, referred to about i per 

 cent, strength, was found to approximate to 0^= +285.7'. 



A fifum (laevulan), dilTering from the foregoing carl>ohy<lnitA\s. 

 was obtaineil by E. Sai.kowski (II.) in 18S9 bv precipitating 

 with Ft'hling's .solution a yeast extnict, prepared with water 

 containing chloroform for the purpose of preventing putre- 

 faction. 



Whilst the umlenialile divergences in the re.snlts ol)tnine«] 

 by the above-mentioned workers compel the .nssun>}»tion that 

 different kinds of gum are pre.sent in different s;imj»les of yea.st, 

 the results of Fiirrz Hesskxi.and's (I. ) experiments permit the 

 further conclusion that several kinds of glutinous carlH)h\di-at*'s 



