SUMMARY AND CONCLUSIONS. 161 



Wiih so unstable a foundation one can not go far in formulating conclusions that 

 can luive more than a tentative value, and with this idea in view the following synopsis 

 of certain especially important points may be made: 



(1) It may be conceded, from the literature herein cited, that the starch-substance is 

 not a uniform body and that it exists in many stereoisomeric forms which vary in the 

 starches of different plants, of different parts of the same plant, of different grains of the 

 same starch, and even of different parts of the same grains; and that in accordance with 

 these variations corresponding differences may be expected in the intermediate derivatives 

 and reversion products in accordance with the stereochemic differences of the homologues. 



(2) That the first step ordinarily, though perhaps not essential, in the saccharification of 

 starch is a liquefaction, and that this is followed serially by the production of erytlirodextrin, 

 achroodextrin, maltose or isomaltose, and glucose, all of which processes, when once under 

 way, go on together, the disappearance of one substrate after another eliminating tlie corre- 

 sponding process, until an equilibrium of solution of maltose and glucose is attained; and 

 that not only may the progress of the reaction be stopped at will, but also, by modifications 

 of the processes, the stages of the degradation of the starch-molecule may be so specifically 

 limited that they do not go beyond the liquefaction of starch, or the formation of dextrins, or 

 the formation of maltose; in other words, these substances are the essential end-products of 

 the reactions in the several cases, so that we may have liquefied starch without the forma- 

 tion of any dextrin, or dextrins without a trace of maltose, or maltose without a trace of glu- 

 cose. This serial action, which results in the formation of an individual substance at each 

 step, finally disposes of the theory of Musculus of the coincident formation by hydrolysis of 

 two substances in the form of dextrin and sugar, and their subsequent cleavage; and it is in 

 support of the theory of Lintner and Diill. We may regard these markedly differentiated 

 steps as representing the major stages, and assume that there are a number of substages. 



(3) That the processes involved in these major stages, as in the case of acids, are due 

 to different functional properties of a single agent; or, as in case of enzymes, either to 

 different functional properties of a given enzyme or to individual properties of different 

 cooperative enzymes, or to both. Sufficient evidence has been offered to show that, at 

 least in some instances, as in the reduction of starch to maltose and of maltose to glucose, 

 two specific enzjines are required, one to yield the maltose and the other to convert this 

 sugar into glucose. It seems likely that four enzymes (or four independent specific prop- 

 erties) are necessary one to liquefy the starch, one to convert the starch into dextrin, one 

 to convert the dextrin into maltose, and one to convert the maltose into glucose. Were 

 we to follow the decomposition processes in the body to the ultimate conversion of the 

 sugar molecules into CO2 and H2O we should find with certainty that still other enzymes 

 are involved, some carrying on very different chemical processes from those stated. 



(4) That all of the processes in acid and enzymic saccharification are those of hydra- 

 tion, but not necessarily of hydrolysis. The swelUng or gelatinization and the formation 

 of pseudo-solution and true solution can be fully accounted for on physico-chemical grounds 

 upon the basis of the adsorption of water, which involves absolutely neither enzymic 

 nor acid activity, nor hydi-olysis, and no hydration in the strictly chemical sense. The 

 reversion of starch when in pseudo-solution or true solution to less soluble forms may be 

 regarded as simply a manifestation of a reversal of the adsorption process and accompany- 

 ing changes which we find paralleled in other of the so-called colloids, and which we obser\'e 

 even in Uving colloidal matter, as in the case of the giving off and taking in of water by the 

 muscle substance, which is assumed by some physiologists to be the essential mechanical 

 part of the phenomena of contraction and relaxation. 



The conversion of starch into erythrodextrin, and of erythrodextrin into achroodextrin, 

 if it be a process of hydrolysis, is of such a character that there is no jjermanent addition 

 of water in the reaction,or, if the product be in the nature of a hydrate, the change is due to a 



11 



