SUCCULENT AND WATERY FOODS 251 



of nitrogenous matter is small, and only a fraction of it is true 

 protein. Fats are absent or present only in very small 

 amount. Potatoes are, therefore, almost entirely a carbo- 

 hydrate food. The coefficient of digestibility is high, and the 

 nutritive value of the whole is very similar to that of sugar 

 beet. 



Forage Crops. Under this head are included all those 

 succulent green fodders of which the edible part consists of 

 the stem and leaf of the plant. Nearly all of them belong to 

 one or other of the three botanical orders, cruciferae, legumi- 

 nosae, or gramineae. They are annuals, and the nutrient 

 substances, accumulated in the stems and leaves by the pro- 

 cesses of vegetation, are to a^large extent exhausted when 

 seed formation occurs. In no case, therefore, should the 

 plants be allowed to develop beyond the stage of flower. As 

 they approach this stage the percentage of fibre rapidly 

 increases and the percentage of water ash and nitrogenous 

 matter is correspondingly diminished. 



These crops vary in composition, perhaps, more widely 

 than those of any other class. Apart from the differences in 

 the several kinds of plant, the variation may be referred almost 

 entirely to the degree of maturity. The leaves contain more 

 nitrogenous matter than the stems, and the proportion of 

 stem to leaf increases as the age of the plants advances. The 

 maturity is also largely affected by external conditions soil, 

 manuring, climate and season. 



As compared with the roots, the forage crops are, on the 

 whole, less watery. The percentage of nitrogenous matter is 

 greater, and a larger proportion of it is true protein; the 

 amount of amides is, however, considerable. The forage crops 

 are more fibrous than the roots, and the coefficients of 

 digestibility are lower. 



The order cruciferae is represented chiefly by cabbage, 

 kohl-rabi, rape, and mustard. The first two are largely used 

 for milk cows. The others are frequently grown as catch 

 crops for which purpose they are peculiarly suitable. They 

 are then generally eaten off by sheep and the residue is turned 

 down. A certain amount of autumn " keep " is thus provided 



