CHAP. I.] CONVERSION OF STARCH INTO SUGAR. 49 



ing it to cool the deposit increases in amount. Under the microscope 

 clusters of yellow crystals are observed. 



* 



When boiled for a short time with a solution of cupric acetate 

 containing free acetic acid, maltose does not reduce it, whilst glucose 

 under the same circumstances partially reduces the solution. 



Barfoetf's Reagent, which is employed as a distinguishing test between 

 maltose and dextrose, is a solution of 1 part of cupric acetate in 15 parts 

 of water; to 200 c.c. of this solution 5 c. c. acetic acid, of 38 per cent., are 

 added. 



Theoretical From the facts which have been enunciated it has 



views as to been surmised by Musculus and Gruber 1 , and by Brown 

 the action of and Heron, that starch is a polysaccharide having a 

 diastatic fer- formula (C 12 H lo O 10 ) n , which under the influence of 



hydrolytic agencies undergoes successive hyd rations and 



decompositions. 



As a result of their researches, Brown and Heron described a 

 series of erythrodextrins and achroodextrins, of gradually diminishing 

 molecular weight, which they believed to be formed during the .process 

 of diastatic hydrolysis, each complex dextrin splitting up into a 

 molecule of maltose and a molecule of a dextrin of smaller molecular 

 weight, and of less complexity. The more recent researches of Brown 

 in conjunction with Morris have not however confirmed this hypothe- 

 sis. According to these researches all the intermediate products 

 which may be separated from a solution of starch which is being 

 acted upon by a diastatic ferment, may be accounted for as compounds 

 of a non-reducing dextrin with maltose. At the same time, as has 

 been already mentioned, there appears under certain circumstances to 

 be formed a body termed malto-dextrin which stands in near relation 

 to the non-reducing dextrin and to maltose, and which, under the 

 influence of a diastatic enzyme, readily yields maltose. 



Brown and Morris believe that the molecule of starch cannot consist of 

 less than an aggregation of 5 times the molecule (C 12 H 20 O 10 ) 3 . They would 

 represent the starch molecule as 



(ciXo'.X 



(C 12 H M 10 ) 3 

 (C, S H 80 10 ) 3 

 (C 12 H !0 10 ) 3 



Under the action of a diastatic ferment the complex molecule gradually 

 is degraded, by successive removals of the ternary groups. 



The removal of each (C 12 H 20 O 10 ) 3 group is accomplished prior to its 



1 Musculus u. Gruber, 'Ein Beitrag zur Chemie der Starke.' Zeitschr. f. physiol. 

 Chem., Vol. n. pp. 177190. 



G. 



OF THE 

 UNIVERSITY 



