898 PRACTICE OF AGRICULTURE. Part III. 



5722. On the nutritive products, Sir H. Davy has the following valuable remarks, some 

 of which, concerning the mode in which the animal economy is operated on by the 

 different substances composing the nutritive matter, the agriculturist will find useful, as 

 applied to the tables before given (5000. 5190. &c.) of the nutritive products of the 

 corns, legumes, and roots. The only substances which Sir H. Davy detected in the 

 soluble matters procured from the grasses, are mucilage, sugar, bitter extract, a substance 

 analogous to albumen, and different saline matters. Some of the products from the 

 aftermath crops gave feeble indications of the tanning principle. In the experiments 

 made on the quantity of nutritive matter in the grasses, cut at the time the seed was ripe, 

 the seeds were always separated ; and the calculations of nutritive matter made from 

 grass and not hay. 



5723. The order in which these substances are nutritive is thus given : " The albumen, sugar, and mu- 

 cilage, probably when cattle feed on grass or hay, are for the most part retained in the body of the animal ; 

 and the bitter principle, extract, saline matter, and tannin, when any exist, probably for the most part 

 are voided in the excrement, with the woody fibre. The extractive matter obtained by boiling the fresh 

 dung of cows, is extremely similar in chemical characters to that existing in the soluble products from the 

 grasses. And some extract, obtained by Sinclair from the dung of sheep and of deer, which had been 

 feeding upon the LMium perenne, Dactylis glomer^ta, and rrifiilium ripens, had qualities so analogous 

 to those of the extractive matters obtained from the leaves of the grasses, that they might be mistaken 

 for each other. The extract of the dung, after being kept for some weeks, had still the odour of hay. 

 Suspecting that some undigested grass might have remained in the dung, which might have furnished 

 mucilage and sugar, as well as bitter extract, I examined the soluble matter very carefully for these sub- 

 stances. It did not yield an atom of sugar, and scarcely a sensible quantity of mucilage." Sinclair, in 

 comparing the quantities of soluble matter afforded by the mixed leaves of the Z,61ium perenne, Z)actylis 

 glomerata, and Trifulium repens, and that obtained from the dung of cattle fed upon them, found their 

 relative proportions as 50 to 13. 



5724. From these facts it appears probable that the bitter extract, though soluble in a large quantity 

 of water, is very little nutritive ; but probably it serves the purpose of preventing, to a certain extent, the 

 fermentation of the other vegetable matters, or in modifying or assistiiig the function of digestion, and 

 may thus be of considerable use in forming a constituent part of the food of animals. A small quantity of 

 bitter extract and saline matter is probably all that is needed; and beyond this quantity the soluble mat- 

 ters must be more nutritive in proportion as they contain more albumen, sugar, and mucilage, and less 

 nutritive in proportion as they contain other substances 



5725. In comparing the co?nposition of the soluble products afforded by different crops from the same 

 grass, Sir H. Davy found, in all the trials, the largest quantity of truly nutritive matter in the crop cut 

 when the seed was ripe, and least bitter extract and saline matter; most extract and saline matter in the 

 autumnal crop; and most saccharine matter, in proportion to the other ingredients, in the crop cut at the 

 time of flowering. 



5726. The greater proportion qf leaves in the spring, and particularly in the late autumnal crop, accounts 

 for the difference in the quantity of extract ; and the inferiority of the comparative quantity of sugar in 

 the summer crop probably depends upon the agency of light, which tends always in plants to convert sac- 

 charine matter into mucilage or starch. Amongst the soluble matters afforded by the different grasses, 

 that of the'lymus arenkrius {fig. 711. a) was remarkable for the quantity of saccharine matter it con- 

 tained, amounting to more than one third of its weight. The soluble matters from the different species 

 of FestUca, in general, afforded more bitter extractive matter, than those from the different species of Phu. 

 The nutritive matter from the seed crop of the Pha. comprt^ssa was almost pure mucilage. The soluble 

 matter of the seed crop of Phlfeum prat^nse, or meadow cat's-tail, afforded more sugar than any of the 

 Poa or Festuca species. The soluble parts of the seed crop of the Holcus mollis, and //ulcus lan^tus, 

 contained no bitter extract, and consisted entirely of mucilage and sugar. Those of the //ulcus odor^tus 

 afforded bitter extract, and a peculiar substance having an acrid taste, more soluble in alcohol than in 

 water. All the soluble extracts of those grasses, that are most liked by cattle, have either a saline or 

 subacid taste ; that of the //61cus lansitus is similar in taste to gum arable. Probably the //61cus lanitus, 

 which is so common a grass in meadows, might be made palatable to cattle by being sprinkled over with 

 salt. 



5727. No difference was found in the nutritive produce of the crops of the different grasses cut at the same 

 season, which would render it possible to establish a scale of their nutritive powers ; but probably the 

 soluble matters of the aftermath crop are always from one sixth to one third less nutritive, than those 

 from the flower or seed crop. In the aftermath the extractive and saline matters are certainly usually in 

 excess ; but the aftermath hay mixed with summer hay, particularly that in which the fox-tail and soft 

 grasses are abundant, would produce an excellent food. 



5728. Anthroxdnthutn odoratum E. B. The proportional value which the grass, at the time of flowering, 

 bears to that at the time the seed is ripe, is as 4 to 13. The proportional value which the grass of the 

 lattermath bears to that at the time the seed is ripe, is nearly as 9 to 13. 



5729. Hdlcus odoratus Host, G. A. The proportional value which the grass, at the time of flowering, 

 bears to that at the time the seed is ripe, is as 17 to 21. The grass of the lattermath crop, and 

 that of the crop at the time of flowering, taking the whole quantity, and their relative proportions of 

 nutritive matter, are in value nearly as 6 to 10 " the value of the grass, at the time the seed is ripe, 

 exceeds that of the lattermath in proportion as 21 to 17. Though this is one of the earliest of 

 the flowering grasses, it is tender, and the produce in the spring is inconsiderable. If, however, the 

 quantity of nutritive matter which it affbrds be compared with that of any of those species which flower 

 nearly at the same time, it will be found greatly superior. It sends forth but a small number of flower- 

 stalks, which are of a slender structure compared to the size of the leaves. This will account, in a great 

 measure, for the equal quantities of nutritive matter afforded by the grass at the time of flowering, and the 

 lattermath. 



5730. Cynosurus aerideus E. B. {Sesleria. ccerulea E. of P. 1070.) The produce of this grass is greater 

 than its appearance would denote; the leaves seldom attain to more than four or five inches in length, 

 and the flower-stalks seldom arise to more. Its growth is not rapid after being cropped, nor does it seem 

 to withstand the effects of frost, which, if it happens to be severe and early in the spring, checks it so 

 much as to prevent it from flowering for that season ; otherwise, the quantity of nutritive matter which 

 the grass affbrds (for the straws are very inconsiderable) would rank it as a valuable grass for permanent 

 pasture. 



5731. Avenq pubescens K B. {Trisltum pubiscens E. of P. 1062.) The proportional value which the 

 grass at the time of flowering bears to that at the time the seed is ripe, is as 6 to 8. The proportional 

 value which the grass at the time of flowering bears to that of the lattermath, is as 6 to 8. The grass of 

 the seed-crop, and that of the lattermath, are of equal value. The downy hairs which cover the surface 

 of the leaves of this grass, when growing on poor light soils, almost entirely disappear when it is cultivated 

 on a richer soil. 



5732. Poa ccerulea var. pi-atensis E. B. If the produce of this variety be compared with that of 



