Oct. I, igig Notes on the Composition of the Sorghum Plant 23 



time is apparent. Collier (5, p. 137) says, "The suckering then 

 of the crop, or at least the careful exclusion of suckers from that 

 portion of the cane which is intended to be worked for sugar, is of the 

 most imperative importance. For sugar production they are far worse 

 than worthless. But they may be used for the manufacture of syrup, 

 since both glucose and sucrose enter into its composition; and, in fact, 

 the presence of the suckers in the crop would very easily prevent the 

 crystallization of the syrup which the manufacturers of syrup frequently 

 find a serious disadvantage." Since the analyses of suckers at this 

 station contribute nothing new to the above facts, they will not be given 

 here. 



Collier (5, p. 225-237) determined the amount of sugars in the top and 

 bottom halves of the cane and found little difference between them. In 

 other experiments he divided the cane into thirds and again found little 

 or no difference in the sugar content. So far as is known by the writers, 

 no one has analyzed each joint separately. Reasoning by analogy to the 

 suckers, the relative immaturity of the upper joints and the relative old 

 age of the lower would lead one to expect a greater concentration of 

 sucrose in the middle joints and of reducing sugars in the top and 

 bottom joints. 



The individual joints of several samples of cane in the dry dough stage 

 were analyzed, with the results shown in figure 16. The concentration 

 of sucrose and of reducing sugars varies inversely; but the variation is 

 not proportional, since the total sugars are far higher in the middle por- 

 tions of the cane. In fact, one of the most significant curves in the chart is 

 that for the total sugars extractable per i ,000 parts of cane. This varies 

 from 21 in the top joint to 46 in the middle and 25 in the bottom.* From 

 the standpoint of sirup making, the top joint, and perhaps the bottom, 

 could well be excluded from the milling, since they contain not only a 

 small amount of sugar but a large amount of nonsugar solids (see the 

 top curve in the graph), which are detrimental to good sirup making. 

 Calculation shows that about 5 per cent of the total sugar would be lost 

 by this practice, but this would be offset by the improvement in quality 

 of the sirup. Went {17) finds about the same distribution of sugars in 

 sugar cane as is reported above, except that there is a continuous increase 

 in sucrose up to the joint next to the bottom. 



In most plant juices the levulose exceeds the dextrose in amount, which 

 fact is usually explained on the ground that the dextrose is more easily 

 utilized in respiration. In sorghum juice the dextrose is always in excess 

 of the levulose. A small portion of this dextrose may represent starch that 

 is not yet polymerized (see next subsection for starch content of juices). 

 It will be noticed that the excess of dextrose over levulose is least in the 



' In explanation of the apparently very small amount of sugars extracted in the cane, it should be stated 

 that this work was done with a small experimental mill which extracted an average of only 33 per cent of 

 juice from the cane, whereas large mills obtain from 60 to 70 per cent. 



