96 CHYMISTRY APPLIED TO AGRICULTURE. 



On the 28th of August, the time of harvest, he plucked 

 up. the twenty plants which had been left for seed, separat- 

 ing the roots, and cutting the stalks as of the first ; of these 

 the weight was as follows, 



Grains. 



Roots 419.53 



Straw, husks, and beards 1318.75 

 Grain 1025.69 



Total 2763.97 



During these two months, the roots and the portions of 

 stalks adhering to them had lost 237.52 



The stalks, head, and leaves had lost 624.67 



Total loss 862.19 



But as the seed weighed 1025.69 grains, the whole had 

 increased in weight 160.47 grains, Troy. From this exper- 

 iment we may conclude, that the juices contained in plants, 

 at the time of flowering, contribute to the formation of the 

 grain in the proportion of -^wTt-iYi ^"^^ that the excess of 

 the weight of the grain, which is yWf .|-f > arises from the 

 nourishment which the plant absorbs from the air or soil, 

 during the two months of fructification. 



If the wheat is mown when in blossom, it leaves in the 

 earth, to be converted into manure, a quarter part of the 

 weight of the plant; but when it is reaped after having 

 come to maturity, there remains only one seventh; and 

 this last residue is worthless as manure in comparison 

 with the first; this contains almost nothing but carbon, 

 whilst that is rich in juices and in decomposable matter. 

 Thus we see that those plants which form seeds exhaust 

 the soil most, because for all they have received they return 

 nothing but their dry roots and stalks ; whilst those that are 

 cut when green give back with their roots and stalks what 

 they have drawn from the soil, and a part of that which 

 they have drawn from the atmosphere. 



The nutritive principles contained in the soil pass into 

 plants only in a state of solution, or of extreme division in 

 water. Healthy plants absorb from preference those salts 

 that are most congenial to them ; but if waters be charged 

 with salts unsuited to their natures, they absorb the fluid 

 and reject the salts till the water becomes thickened by 

 them. 



