74 



THE CHEMISTRY OF THE FARM. 



seed, the variations in composition are not generally con- 

 siderable, and an average composition, such as is given in 

 the table, will be found in most cases pretty correct. But 

 in the case of immature produce, such as meadow grass, 

 turnips, or mangels, the composition largely depends on 

 the stage of growth in which the plant is taken, and is 

 also greatly affected by the character of the manuring. It 

 may be generally stated that as a plant matures the pro- 

 portion of water, nitrogenous matter, and ash constituents 

 diminishes, while the proportion of carbo-hydrates largely 

 increases. At the same time the amides become more or 

 less converted into albuminoids. 



The following table shows the percentage composition of 

 meadow grass cut at three different dates in the same field. 

 The first cutting will represent pasture grass fed off in the 

 green state by stock ; the second cutting is good ordinary 

 hay; the third cutting is an over-ripe hay, somewhat 

 coarse and stemmy, but well harvested. The composition 

 given in every case is that of the dry substance : — 



COMPOSITION OF HAY HARVESTED AT DIFFERENT DATES. 



Young grass is thus much richer in albuminoids,* and 



* It must be bome in miud that in the present transition state of our 

 analyses of food, the tei-m ** albuminoids" will generally include all the 

 nitrogenous substances present. 



