80 The Feeding of Animals 



The pectin bodies. Another class of compounds 

 much like the gums, and perhaps related to them 

 chemically, is the pectin bodies. Some of these sub- 

 stances are gelatinous in appearance. The jeltying of 

 fruits, such as apples and currants, is made possible by 

 their presence. They exist in greater abundance in 

 unripe fruit than in the ripe, consequently the former 

 is selected for jelly -making. When such fruits are 

 cooked, the pectin which they contain takes up water 

 chemically and is transformed into a gelatinous sub- 

 stance, and the secret of jelly -making is in stopping 

 the cooking process before the chemical transforma 

 tions have passed beyond a certain point. Mucilages 

 not greatly unlike the gums and pectins exist in cer- 

 tain seeds and roots, the most notable instance being 

 flaxseed. 



The sugars. When considered from the stand- 

 point of efficiency, the sugars are the most valuable 

 of all the carbohydrates, although in quantity they are 

 much less important than the starches, because they 

 are found only in small amounts in the hays and to a 

 scarcely appreciable extent in the grains. Certain dis- 

 tinctively sugar plants, to be mentioned later, are 

 grown agriculturally, which are sometimes used as 

 cattle foods. 



Unlike starch, the sugars are found in solution in 

 the sap of growing plants. It is probable that these 

 are the forms in which carbohydrate material is trans- 

 ferred from one part of the plant to another. It is 

 easy to see that some such medium of exchange is 

 necessary. The actual production of new vegetable 



