44 ■ SECTIONAL ADDREvSSES. 



One objection may, however, be discussed. In the formation of 

 maltose no more than one molecule' of this disaccharide could be obtained 

 from one such unit. The maxinuim yield of the sugar would there- 

 fore be of the order 70 per cent. (74 per cent, calculated as maltose 

 hydrate). Yields higher than this figui'e are quoted in the literature, 

 but it may be remarked that most specimens of maltose do not behave 

 as identical homogeneous chemical individuals in bacteriolo'gical tests. 

 Fm-ther, von Euler and Svanberg,-* who conducted the diastatic 

 hydrolysis of starch under conditions in which the optimum hydrogen 

 ion concentration was present, i-eport that the yield of maltose formed 

 is then 75 per cent. The small margin unexplained by our fonnulse 

 may be due to the synthetic action of the enzyme on the molecule of 

 glucose liberated during hydrolysis. This suggestion is in agreement 

 with von Euler's observation that the end point oi his reaction was 

 reached with extreme slowness. Another objection tO' the new sti-ucture 

 is that the acetolysis of starch might result in molecular rupture in 

 such a manner that cellobiose would be produced. So far, this 

 disaccharide has not been encountered in the degradation products of 

 starch, ai result which is not surprising in view of the uncertainty 

 attending the formation of cellobiose. It may also be mentioned that 

 if starch is composed uniformly of the above anhydro-trisaccharide 

 residues it is difficult to explain the existence of polyamyloses other 

 than those to which the general formula (CeHioOj^,, can be applied. 

 Taking into consideration the yield of di- and tetra-amyloses obtained 

 from starch, it is evident that they may possibly be accounted for in 

 the fraction of the starch molecule which has not yet been converted 

 intO' recognisable glucosides, but the ariernative is also open that the 

 polyamyloses may not all be structurally related to starch. 



It is perhaps advisable tO' point ont that the experimental results 

 now presented demand the i-ejection of various formulae for starch 

 proposed from time tO' time by Karrer. His structures are based on a 

 diamylose fanhydro-maltose), twO' formulae for which have been put 

 forward differing in the position of the anhydro-ring. The evidence 

 he adduces in favour of these views is not convincing. 



The first unit he gives is : — 



I 1 



CH,OH • CHOH • CH • CHOH • CHOH • OH 



1 

 O XX. 



I " I I 



OH ■ CHOH • CHOH • CH • CH- CH. 



I - -- O I 



A formula of this type is open to many criticisms, and would 

 demand the direct ])roduction of 2,.'3,5,6-tet.rametIiyl glucose from 

 a methylated starch. It is needless to state further objections, as 



