44 MA^^UAL OF CATTLE-FEEDIN-G, 



Tliey all resemble, in a general way, cane-sngar in tlieir 

 properties, though they are by no means identical. 



For our present purpose, it is sufficient to say that they 

 are all readily soluble in water, and hence easily digestible. 

 They are important nutrients, being formed in large quan- 

 tities, in digestion, from other carbhydrates, though in the 

 ordinary fodders they occur in only small quantity. 



The Gums. — Another group of substances of consider- 

 able importance is the gums, of which gum-arabic may 

 be taken as a representative. 



They are found in small proportions in various vegeta- 

 ble products, and in considej^able quantity in the ordinary 

 bx^ead grains. They appear to be digestible by domestic 

 animals, but of their value as nutrients we know as yet 

 but little. Probably, however, they are practically about 

 equivalent to starch. 



Mutual Relations of the Carbhydrates. — The close 

 relationship between the several members of this group of 

 substances which is indicated by their analogous composi- 

 tion is shown still more plainly both by their ready con- 

 version one into another, in nature and in the laboratory, 

 and by their behavior to various reagents. 



In the plant, starch seems to be the first formed, and 

 from it all the other carbhydrates are produced, while 

 these may be converted back again into starch. 



In germination, the starch of tlie seed is convei'ted into 

 dextrine and sugar, which are carried in solution to the 

 young plant, there to form cellulose or be reconverted into 

 starch. In older plants, cellulose may be dissolved or con- 

 verted into gum or vegetable mucilage. 



In the laboratory, all the vainous carbhydrates are finally 

 converted by heat or by boiling with acids or alkalies, first 

 into dextrine and then into some form of sugar. 



