Oldalképek
PDF
ePub

1st. By the different nature of the straw, in respect to its kind and variety.

2d. By the larger or smaller amount of grains remaining in the ears in threshing.

3d. By the more or less perfect separation of the more nutritious chaff and blades from the ears in threshing.

4th. By the varying state of maturity of the straw; the riper it is, and the longer it stands before it is mown, the less nutritious it will be.

5th. By the fact that the straw of summer crops is one-fourth more nutritious and valuable than that of winter crops.

6th. By the condition of the weather; whether it is housed dry or moista

7th. By the condition of the land on which it grew: a well manured, powerful field produces a more nutritious straw.

8th. By the amount and nature of the grasses intermixed with it and grown among the crop. Straw intermixed with a large amount of young clover, may prove twice as nutritious as otherwise.

As to the kind of straw, that of summer barley and oats is deemed the most valuable for feeding purposes, which is also in accordance with the analyses. The next is that of summer wheat and winter barley; that of winter wheat is inferior, and rye straw has the least value of all. But this rule is sometimes subject to exceptions in special cases: thus it frequently happens that rye straw is better than oat straw of the same season, and contains more protein substances.

Chaff contains less woody fibre, and decidedly more protein substances and mineral salts. The proportion of the nutritive substances in it is, therefore, as 1 to 9, which makes it a tolerable fodder for cattle. In an economical point of view, one part of hay is equal to two parts of chaff, and to three parts of straw.

Straw and chaff contain but little fatty matter, on an average hardly more than one per cent., except oat straw, which has three per cent of fatty substances.

What nutritive value has stray in general? If we were to answer this question according to these analyses, and if we would base our calculation upon the 2.6 per cent. of protein and 31.5 per cent. of soluble non-nitrogenous combinations in straw, it would be very simple, but the result would not be reliable, for it would be too favorable in comparison with the experiences of farmers, and it would not agree with the more recent investigations of the digestibility and the nutritive value of the various constituents of straw.

We know that a large portion of this 31.5 per cent of soluble nonnitrogenous combinations has no nutritive value at all, and that a no less considerable portion of 45 per cent. of woody fibre, which were considered insoluble and indigestible, according to our former analytical methods, are actually dissolved by the digestive juices of cattle and sheep.

According to investigations as yet very limited, the amount of worthless non-nitrogenous constituents of straw varies between 3 to 4 of three con. stituents proved soluble by analysis ; it, therefore, amounts to 10 to 15 per cent. of the weight of straw, and only 15 to 20 per cent. remain for the oategory of sugar, being of nutritive value.

As to whether the 2:6 per cent. of nitrogenous substances found by sum. mary analysis must be reduced at the same rate, is not stated as yet, but it is believed that those nitrogenous substances calculated by the amount of nitrogen approximate more the constitution of the pure nutritive proteïn matter, and are, at most, to 4 of their amount intermixed with worthless nitrates, ammoniacal salts, alkalies, chlorophyll, and wholly indigestible particles of proteïn. In any other fodder, except straw, this worthless portion must be of another proportion, because the amount of heterogenous nitrogenous substances is different in every kind of fodder. Besides, any fodder containing much woody fibre produces excrements containing different amounts of protein matter, which could not be the case, if the nitrogenous substances in every kind of fodder were digestible in an equal degree. Yet we have no positive knowledge of their propor. tions, and it will require yet much labor and investigation before we can determine what proportion of the nitrogen contained in every one of the principal kinds of fodder has no nutritive effect.

As to the analytical amount of woody fibre, the recently established fact, that a portion of it is aigestible is far from being satisfactory. We must also know the nature of the combinations originating from the digestion of the woody fibre, and their nutritive value. It is believed by some that the substances resulting therefrom probably are of a saccharine nature; but they may perhaps be substances similar to those which are found in the analytical column of the soluble non-nitrogenous combinations, and have, as before stated, no nutritive value at all.

By these remarks every one must see how little light the above analyses of straw give us in respect to the actual nutritive value of straw; nay, it may be added that the analyses of no other fodder have furnished so unsatisfactory results as those of straw and similar productions containing much woody fibre. Accordingly these analyses of straw have not determined anything positively but that, in general, straw is a fodder containing but a small amount of protein, and will not satisfy the wants of protein in any productive animal fed with it exclusively. A milch cow, for instance,

in order to obtain her daily requisite amount of 24 lbs. of proteïn, would have to consume about 100 lbs. of straw, which is impossible for her to do; and even if she could do it, this method of feeding would be objectionable economically, for it would be a useless waste of non-nitrogenous nutritive matter because no animal will, for any length of time, assimilate 12 parts, but 7 to 8 parts only of the latter to every 1 part of proteïn. The remaining 4 parts of so-called hydrates of carbon may be made useful only, if a food rich in proteïo (oil-cakes, pulse, bran, clover hay, &c.) is mixed to straw.

According to these views of the nutritive value of any substance, the physiological value of straw is wholly dependent upon other incidental substances constituting the ration of an animal.

[ocr errors]

MICROSCOPIC RESEARCHES:

Resulting in the discovery of what appears to be the Cause of the so-called Blight in Apple, Pear and Quince Trees; and the Decay in their Fruit, &c.

BY J. H. SALISBURY, N.D., AND O. B. SALISBURY.

Commencement and Progress. During the summer of 1862 the blight began to affect the apple, pear and quince trees in Central Ohio, about the 12th of June. It made its appearance suddenly, after warm moist weather. Its invasion and progress was identical with the attack of blight which was so destructive to apple, pear and quince trees in 1847 and '48, throughout the Northern and Eastern States. At different elevations, the trees were affected in different degrees. Generally on, and, for a short distance, above the third terrace from the stream bottoms—which corresponds with the line of suspended stationary vapors and fogs—the trees were much more affected than at higher or lower levels.* Some trees in an orchard would be affected much more than others adjacent on the same level. Often the more thrifty trees and most vigorous sprouts, would be the ones the most invaded. Sometimes twigs and limbs would commence dying at their extremities, and this death would gradually advance towards the base of the limb, always advancing faster in the layer of new soft wood and bark (cambium) than in the more solid heart wood. At other times the death would commence in the middle of a limb-often several feet from its extremitykilling the new wood and bark first, and gradually advance from the point of starting, up and down the limb, leaving the heart wood sufficiently alive to communicate, for weeks, sap enough past the diseased and dead surface rim, to support the vitality of the extremity. In other instances, a surface-patch, merely, on the side of the limb, would die. This disease progressed till about the first of August, when its advance seemed to be checked by the tissues of the young wood becoming too firm for the further invasion of the fungus.

* In our examination of rich peaty, wet low grounds and bogs, with the view of determining the character of the malarious matters produced by them and elevated in the fogs and night vapors rising therefrom, we found the fungus, which is the cause of the apple, pear and quince blight, &c., growing luxuriantly on and in the peculiar, palmelloid, algoid growtbs, that are so prolific upon the broken-up sod and surface of rich bogs. (These palmelloid growtbs, with their parasitic fungus, will be fully described in a paper, which will soon be ready, on the Cause of Intermittent Fevers, &c.) The occurrence of the apple, pear and quince tree blightfungus, so abundantly in positions where their spores are liable to be elevated in every rising fog or night vapor, and the further fact, that trees are more affected with blight along the line of elevation described by the stationary night and morning vapors, points strongly to the boggy grounds as one source of this destructire fangas.

In our office yard were several apple trees affected with the blight. We selected several limbs for observation, which began to die near where the spring's growth commenced. These limbs were first affected between the 12th and 15th of June. Death gradually advanced both towards the base and extremities of the limbs, till on July 14th the limbs were all dead to their extremities. July 15th, cut off the limbs for dissection and microscopic examination. Found the entire limbs, through and through, at the point where the blight commenced, filled with the mycelium of a peculiar fungus. The threads wound around in every direction among the woody cells; and where there were intercellular spaces, these were filled with the moniliform threads, fig. 3, Lignograph A.* In passing up or down the limbs, the same appearance was presented, save that the fungus was more and more confined to the new layer of wood as you departed from the point of attack. For several inches beyond (in the tender, rapidly growing twigs), where the limbs were not actually dead, dead lines, the size of a knitting-kneedle, extended in the soft viscid, gelatinous matter (cambium), which was to form the new annual layers of wood and bark. Along these dead lines could be traced the moniliform threads, making their way among the cells.

Fig. 1, Lignograph B, represents a portion of a transverse section of the limb of an apple tree, affected with blight. This section was taken about $ inch from the live portion. It will be seen that here the young plants are making rapid headway among the cells. In the center of this slice is an intercellular space, filled with short moniliform threads.

Figs. 3 and 5, Lignograph C, represents a portion of the moniliform filaments in a part of the limb that had been dead since June 15. This portion of the branch was much shrunken; and in the intercellular spaces and between the cells, occur these moniliform (mycelium) threads, winding about and knit together in various ways.

Fig. 6, Lignograph D, a longitudinal section of wood immediately beneath the bark; showing short moniliform threads in the interstices between the vessels.

Figg. 2, 4 and 7 (Lignographs B, C and D), fungoid filaments found in a single intercellular space of the wood of a dead twig. Fig. 4 represents the same species as figg. 3, 5 and 6. Figs. 2 and 7 represent fangi that we < have found only in portions of twigs that have been some three weeks or

* The Lignographs or engravings will be found on pages 473 to 479.

« ElőzőTovább »