ORGANIC COMPOUNDS OF PLANTS 1 95 



256. Gums. Closety related to the sugars are the 

 gums, like gum arabic, and those which exude from 

 peach and cherry trees. In the seeds of many grains, 

 there are also gum- like bodies. When treated with di- 

 lute acids, the gums are converted into dextrose sugars 

 and acid products. Bassorin, or mucilage, as flaxseed 

 mucilage, is found in a few seeds and fruits. The for- 

 mula for some of the gums is the same as for sucrose sugars 

 and dextrose. 



287. Pentosans The pentosans are a class of carbo- 

 hydrates present in liberal amounts in many plants. They 

 are insoluble, and aid the cellulose in giving form and 

 structure to plant tissues. When acted upon by dilute 

 acids, the pentosans are rendered soluble, while true cel- 

 lulose is insoluble. They are called pentosans because 

 they yield a sugar which contains five atoms of carbon 

 in the molecule. When acted upon by the digestive 

 fluids they are rendered soluble and available as nutrients. 

 In some fodders they form a large part of the nitrogen- 

 free extract. The digestible pentosans are considered as 

 having the same food value as other digestible carbohy- 

 drates. The amount of pentosans in some common foods 

 is approximately as follows : 



Per cent. 



Hay, timothy 20 



Linseed meal 12 to 15 



Wheat bran 17 to 22 



Wheat 4 to 6 



Oats 12 



Corn 5 



Barley 5 to 7 



Flour- ,. trace 



258. Peptin Bodies are present in many ripe fruits and 



