CHEMICAL BASIS OF THE ANIMAL BODY. Jll 



where the aeti\t- ai;ent is without doubt an en/yme. 1 From 

 this it appears that cane-sugar conforms to tin- apparently 

 ral rule that the carbohydrates leave the alimentary canal 

 as dextrose. 



( 'ane-sugar readily undergoes a lactic-acid fermentation in pres- 

 "f sour milk to which /inc. oxide is added for the fixation of 

 the acid as u is formed. 



1*. Maltose. <Y.Il,,<> u + H, >. 



This is the sugar which is characteristically formed, together 

 with de.xtrins, by the action of malt-extract (diastase) on star< -h- 

 paste. It was first described by Dubrunfaut 2 as arising in this 

 I >ut its existence was for some time doubted until firmly 

 established hy O'Sullivan. 3 Later researches showed that it is 

 similarly the chief sugar which is formed by the action of saliva 

 ami pancreatic juice upon starch-paste or upon glycogen, being 

 accompanied in the case of pancreatic juice by a variable but dis- 

 tinct amount of dextrose if the action of this secretion be pro- 

 li-n -'-.I.* Maltose is also formed by the action of dilute acids 

 ujM.n stan-h-j aste, but in this case it is difficult to prevent the 

 simultaneous formation of dextrose into which it is readily con- 

 verted by acids, yielding 98 99 p. c. of the latter sugar. 6 It is 

 therefore usually prepared from the products of the action of malt- 

 extract on starch -paste. 6 



.Maltose is very soluble in water, also in alcohol, but less so in 

 the latter solvent than is dextrose. It crystallises in fine needles 

 which are however not very easily obtained. Solutions of maltose 

 are dextro-rotatory ;,,,,! reduce metallic salts; it is therefore not 

 easily distinguished from dextrose by merely qualitative tests. 

 A< tii- nerv-^ity of discriminating between the two sugars is one 

 I iient ocrurrence, the following characteristic differences be- 

 tween their optical and reducing powers are of great importance. 

 For maltose in 10 p. c. solution at 20C. (a) D = + 140 , 7 tor dex- 

 trose (a) D = -j-52'5. When maltose is boiled with Fehling's 



Yin-how's Arch. Bd. x. (18. r .f,|. S. in Koebner, Diss. Breslau, (1859). Al.st. in 

 Ili-iili- 11 Metaner's Jahre* _' .'.. 



;il><-. <;,,tr,,n,. i. ,1 ,.</. H'/v. isf.s, S. 289. Pjisrliutin. Air/,. /; .{nut. H. 

 AVi//..W. .Jahri,'. (1*71). S. :C4. Bernard, '.':. /'./. </. J'<n-i*. l.*7.'!, p. -.'(Ml. Br.\vi, 

 iin.l M.-n.n, I,i-l.ii;'s .\nn. IM < . i\ ( I - ..MM. 1880, 



p. 393 Vi-ll:i. M.-li-sclmtt's r,,t.r*,t,-l,. \M. Mil (\^\). S. 40. 



('/,,,. ,t /'/M/.S-. (:t) T \\i (1841 , p 178 



' .//. ('! J. \..l \. (lx7i>l, p. :.7'.i. Cf. Musmlii> u (Jriilx-r. '/A 



;/.sW. t /,. B<l u. (1-7- 7'M. S. 177. 

 1 Mus< iilu-i ii \<Hi M.-riiiL,'. '/J. /'. II/II/SKI/. <'li- in. IM i. (1877-78 ).S. :'.i:i: ii (1878), 

 Kill/.. iMlii^'-r's .!//!. IM \\i\ (1--<I ). S. SI. I'.n.wn :ui.| Hrn.n, I.n-l.i-'> 

 Ann. IM. v 



:i<M. von MoriiiR, Zt. f. vhi/tiol. Chem. IM. v. (l*sl), S. 185. 

 . r.Cktm. CJi, IM. \\\ - iu. 



8 Soxhli-t. Jn.f.pr. L'hrm. (2), IM. XXI. (18SM). IliT/.fi-ld. I.ii-l.i-V Ann. Bd. CCXX 

 (1884), S. I'll. 



7 Metal, loc. cit. Brown and Heron make it lew = +135*4. 



