50 



THE FARMER'S MAGAZINE. 



progressive changes which the sap undergoes. For the 

 convenience of the reader we have only given the first 

 and last analyses of the leaf and straw, and to this is 

 added the analyses of oat straw when fully ripe. 



ANALYSES OF OAT LEAVES 



Silica 



Pliosphoric acid .. 

 Sulphuric acid.. .. 



Lime 



Magnesia 



Peroxide of iron .. 



Potash and soda.. 



Chloride of sodium 



and potassium .. 



These analyses show some remarkable changes in the 

 mineral matter present. The leaf and stalk on the 4tli 

 of June in many respects show a similarity of compo- 

 sition ; but after this the leaf appears to go through its 

 changes more rapidly than the stalk. We observe the 

 plant gradually surrendering its phosphoric acid and 

 its alkalies, potash and soda, for the grain, and in- 

 creasing in its proportion of silicates, upon which it 

 relies for strength and protection. The large increase 

 of potash and soda in the stalk on the IGth of July 

 may be traced to the vigorous action of the plant in 

 supplying these bodies to the seed, rather than to any 

 increased deposit at this time. An early cutting there- 

 fore modifies the composition of the ash, and would in 

 some degree improve its value as a manure, but have 

 little iniiuence on its nutritive powers. 



The climate of the district in which corn may be 

 grown exerts a yery powerful influence upon the 

 quality of straw. Oat straw grown in the North of 

 England and Scotland Is very different in quality from 

 that grown in the South and East of England, and the 

 same with other kinds of straw. The feeding quality 

 of straw will generally be found to be best when grown 

 in the district best suited for the successful growth of 

 the corn it bears. Thus, upon high, cold, and exposed 

 tracts of land, rye straw is very superior, and preferred 

 by stock to any other kind of straw. Oat straw often 

 contests this preference, and, as the land gets stronger 

 in character, the latter gi-adually becomes superior. In 

 other districts both of these arc considered inferior to 

 •wheat and barley straw ; so that there is no constancy 

 in the preference shown for either variety. It may 

 howeverj be inquired if this prejudice in different 

 localities can be taken as evidence of variation in feed- 

 ing qualities ? It is believed by some persons that the 

 preference shown by stock is at the present time more 

 satisfactory evidence of variation in feeding value than 

 any other tests we can apply j and we must admit that 

 we know but little just now of the feeding value 

 of any body except as the result of actual experi- 

 ment, and these results contradict the general opinions 

 held with respect to the estimation of their feeding 

 powers. For this reason— taking the indication given 

 by stock in preferring difierent kinds of straw in dif^ 

 ferent districts, as proof— the value of straw as food 

 does change, according as the soil and climate become 

 more or less suitable for its growth. 



The organic analyses of straw whieh have been pub- 

 lished, show that the different varieties vary but little 

 in general composition. 



Per cent. Mean. 

 The nitrogeuised matter varies from 1.87 to 2.5 = 2.19 

 The carbonaceous „ 91.3 to 94.53= 92.6 



. These are comparatively close results, but we have 

 reason to believe that the composition of straw varies 

 as much, if not more, in the same variety, as it appe-ars 

 to do between different varieties ; that the influence of 

 soil, climate, and ripeness at the time of cutting make 

 greater differences than ai'c here shown to result from 

 distinct varieties. We may, however, examine into 

 these analyses, and inquire what is represented by the 

 two classes of bodies respectively distinguished as the 

 nitronised and carbonaceous groups. The nitrogenised 

 group consists chiefly of albuminous matter, and we 

 may fairly consider straw to possess on the average 

 2.19 per cent, of flesh-forming food. The carbona- 

 ceous group does not consist of matter in an equally 

 available form. In the early growth of vegetable 

 matter we have a body present known as cellulose, 

 and of such the cells of the plant are built up. This 

 matter may, under certain conditions, be retransformed 

 into starch and sugar, and become useful for the sup • 

 port of animal heat, and the formation of fat ; but in 

 proportion as the plant gets older, this cellulose 

 becomes charged with incrusting matter; its charactei? 

 alters, and it becomes known as woody fibre. This 

 cannot be rendered available for the wants of the body 

 by means of digestion. Although the elementary 

 composition of this carbonaceous matter differs but 

 slightly from that of starch, gum, sugar, and oil,andmay 

 undef the action of powerful chemical agents, be 

 transformed into the former of them ; still the mild 

 action of the digestive powers do not render it available 

 as food. Any carbonaceous matter which may exist In 

 its earlier stage, either as oil, dextrin, starch, or sugary 

 would be readily available ; but having passed through 

 these conditions, and become appropriated by the 

 plant in a more advanced stage of transforniallon, it 

 cannot be brought back again so as to be available for 

 the purposes of animal life, except by a decay which 

 will not take place in the body. The 02.6 per cent, of 

 carbonaceous ingredients comprise a large quantity of 

 matter which cannot take part in nourishing the body; 

 and in order that we may judge rightly on the matter, 

 we need information respecting the constituents Vphidh 

 are thus grouped together. Professor Johnston has 

 quoted some analyses of Dr. Sprengel respecting the 

 composition of wheat, batlcy, and rye straw, as nearly 

 Identical in composition ; but more recent analyses by 

 Mr. Nesbit give a very different estimate of theil- in- 

 gredients. We shall take an early opportunity of 

 pursuing this inquiry, so as to show its infltience upon 

 the absolute feeding value of straw. 



