84 Kansas Academy of Science. 



Fremy, obtained pectin from crabapple, grape, sweet-apple 

 and peach juices, and from the white inner skins of oranges 

 and lemons. The uncooked juices of apple, quince, lemon and 

 orange, according to Goldwaite, did not contain pectin, but 

 the uncooked fruit juices of currants and blackberries did con- 

 tain pectin. It has long been known that the cooked fruit 

 juices of apples, quinces, currants, blackberries, crabapples, 

 grapes, plums, raspberries, peaches, barberries, cranberries, 

 blueberries, pears, and, with care, cherries and stawberries, 

 contain a substance which will form a jelly. Where the proc- 

 ess of jelly making originated is not definitely known. The 

 pectin, or the jellying principle, is still unsolved, but Bigelow, 

 Parloa, Goldwaite and Leach have stated that in their opin- 

 ion pectin is supposed to be a carbohydrate, similar in its 

 properties to starch, while Herzfield regarded the pectin 

 bodies as combinations of araban and galactan, and Tollens 

 has suggested that they may be glucosides. All investigators 

 have agreed, however, that the pectin is the gelatinizing agent. 

 The principal theory is that pectose and pectase always exist 

 in the unripe fruit, and when the fruit ripens the pectase acts 

 upon the pectose, which is insoluble in water, converting it 

 into pectin, which is soluble. Pectin is at its best when the 

 fruit is just ripe or a little before. The French chemist Man- 

 gin divides the pectose groups into two series: (1) Neutral 

 bodies which vary in their solubility in water. At one ex- 

 treme we have the substance pectose, which is insoluble in 

 water and closely associated with cellulose ; at the other ex- 

 treme the substance known as pectin, which is soluble in water 

 but tends to form a jelly fairly readily. Intermediately be- 

 tween these are bodies of a gelatinous nature. (2) Sub- 

 stances allied to this group are feeble acids, the chief member 

 of which occurs as calcium pectate ; the latter forms a binding 

 substance between the pores of many plants. 



Decomposition of pectose bodies. Wienogradski and his 

 pupils say it is due to anaerobic bacillus which will decompose 

 pectin and calcium pectate, but has no action on cellulose. 

 Flax is held together by an integument consisting of calcium 

 pectate. This is gotten rid of by a fermentation process which 

 decomposes the integument while leaving the fiber intact. 



This important enzyme — -pectose — which gelatinizes fruit 

 juice containing pectin, plays an important part with calcium 



