330 PLANT AND ORGANIC CHEMISTRY 



of the left one, for by no possible turning can the configura- 

 tion of the one be superimposed upon the other. Thus they 

 are called enantiomorphic; but united, they give the modifi- 

 cation towards polarized light. The inactive glucose may be 

 again decomposed into the two active forms. 



The question naturally arises, Why are these configura- 

 tions represented as they are on the diagram ? x It would carry 

 us beyond the time allotted for this occasion to go into the 

 reasonings for each case. I will only take one or two exam- 

 ples. But it may be stated generally that the observations 

 made on these sugars from experimental facts are in accord 

 with theory. 



On the chart, beginning at the top of the diagram, are the 

 two triose sugars, each with one asymmetrical carbon. On 

 the next lines are the four tetroses, which have been made syn- 

 thetically. There are eight pentose sugars having three asym- 

 metrical carbons; and below these are represented the six- 

 teen hexose sugars, to which glucose belongs. I have not 

 considered it necessary to continue the representation of the 

 higher sugars on the chart. 



But suppose that I should change the aldehyde group of 

 these sugars into a corresponding alcohol group, it would be- 

 come apparent that the conditions for asymmetry were changed. 

 Each of the end carbon atoms, in its atomic relations, is alike, 

 and these alcohols contain only two asymmetrical carbons. 

 The configurations for the pentose sugars, one and two, here 

 given, are unlike. They are the mirror images of each other. 

 When reduced, however, to their alcohols, the identity of the 

 alcohols arising from these two sugars becomes apparent on 

 turning the end group of one df the compounds in the plane 

 of the diagram, and bringing this group to the top of the other 

 configurations. Also, if these alcohols are imagined to be the 

 acids of the group, the tri-oxyglutaric acids, the (CO OH) 

 groups standing at each end of the carbon chain when the acid 

 is turned in the same plane on the diagram as the alcohols, 

 it will be seen that one acid configuration results from two 

 sugar ones, as in the former case of the alcohols. 



1 See Table I. 



