SWATH SHOCKS.-Swath shocks have this advantage over sheaf shocks that they may be made at any time and in any condition of the grain, dry or moist, clean or full of weeds. They are made in the following manner: take a stake about four feet long, sharpened at one end, and pierced with two holes at the upper end, one above the other, so that two poles about three feet long may be put into them in the form of a cross-place the swath grain in this cross, slanting it more and more until a cone of four or five feet in diameter at the base has been formed, then withdrawing the poles and lifting out the stake, put on a cap formed of a reversed sheaf. If there be fear of winds the cone may be surrounded by a band of straw a little below the heads.

In well made shocks grain may be safely kept for months, in all weathers, and its preparation does not require much more time than the labor of binding, which is then done.

Having now adverted to the terrestrial, atmospheric and agricultural causes effecting injuriously the productiveness of the wheat crop, in the present or preceding portions of this article, we will now proceed to a consideration of those causes of injury which we have seen fit to call constitutional, or those to which the wheat plant is by its nature exposed, and which although susceptible of very great modification, by properly applied knowledge are nevertheless, in the present state of agricultural science not wholly remediable by human ingenuity.

The simple diseases of wheat inherent in the nature of the plant itself, and not produced by something superadded, are but few and unimportant, but by nature wheat is exposed to the attacks of diseases whose ravages are very great, which are caused by agents which are independent existencies, so to say; that is, by organisms which affect the plant by feeding upon its nutricious juices and destroying either its vitality or perverting its development to such an extent as to make it unfit for the accomplishment of the purposes for which it was designed. These agencies are known as parasites, that is organisms which draw the materials for their nutrition and growth from some other organism, which they either injure or destroy by robbing it of its vitality for the support of their own being. These parasitic organisms are divided into two classes, vegetable and animal, and a description of the more prominent and important of the individual varieties belonging to these two classes, will make up the remainder of what we have to say in regard to the most important of all vegetable production, the wheat plant, and although we will be compelled to condense what might, from its importance fill many pages, into a comparatively small compass, yet we hope to be able to point out such practical

and useful indications of the causes and cures of these maladies as to lead agriculturists to study more carefully the nature of these diseases, and their appropriate remedies, in order to make the production of the wheat crop a more certainly remunerative investment of time and labor than it is now.

Before entering upon a consideration of the diseases of wheat, caused by parasites, it seems proper to make a few remarks upon the subject of the

DEGENERATION OF WHEAT.-It has long been held in a traditionary manner that wheat degenerates, and that there is an inherent tendency so to say for wheat to change in variety in certain circumstances, but this is an error. The causes which operate to enable chess to supplant wheat are alike active to cause one variety of wheat to supercede another, and a reference to the arguments upon the subject of chess will be a sufficient guide as to the principle involved.

The more prolific varieties of wheat when mixed with the less prolific, bringing forth proportionally more grains, will in a few successive crops give a pe cnderance to the more prolific varieties, and in the end supercede entirely the others, and thus without one variety being transformed into another, the character of the crop may be entirely changed in a few years, by the presence at first of so small a number of grains of the less desirable but more prolific varieties, that their existence was unnoticed in the seed altogether.

The only means of preserving a variety of wheat pure, is to be exceedingly careful in the selection of unmixed seed, and if this be done continually no deterioration or change of variety can occur. The time will come, perhaps soon, when such a nice appreciation of the aptitude of dif ferent varieties of wheat for particular soils, will be attained, that, to obtain such varieties as are suitable for particular localities, wheat nurseries will be established for the purpose of procuring and preserving all desirable varieties of seed wheat, as is now done to secure proper seed from which to raise plants of other genera.

Besides this mode of change in the variety of wheat grown upon a single farm or in a particular district, there is another mode in which wheat is gradually changed by the influences of soil, climate and manner of cultivation, as from red to white, from winter to spring, or awned to beardless wheat, and for such changes, if not desirable, a change in the mode of cultivation, as to manuring, plowing, time of sowing, &c., will prevent their occurrence, or if skilfully directed efforts are applied, favor such alteration in the character of the plant as may be desired; but, the easiest

method, perhaps, of keeping up a particular variety of wheat is to import seed as often as deterioration is becoming evident, from some northern district where such variety grows habitually. Wheat assumes the character of a new variety, but very slowly indeed, under the influences of climate and soil, but yet such a change may in time be effected, as we have reason to believe that all varieties of the plant are the result merely of causes continuing for a long time in operation, and producing all the kinds of wheat now in cultivation from one or two original varieties, but no specific change has ever occurred in this plant, and all its varieties remain mere varieties, and could be reproduced again and again if lost by a compliance with certain conditions, now known or yet to be known.

VEGETABLE PARASITES.-Every creature which fixes itself upon another creature for support or nourishment, has received the name of parasite. Parasites pass through all or only a part of the phases of their existence, upon the individuals where they have been deposited in the shape of eggs, grains or spores. True parasites are those which live at the expense of the juices elaborated by the plants which support them, as the mistletoe, broom-tape, and a great number of mushrooms, &c., while the false parasites are those which merely find a point of attachment and support upon the plant to which they adhere, and which thus live as well upon one individual as upon another, as the ivy, and various other creepers.

Among the false parasites we do not know any that have been remarked as causing damage to a great extent, although they are sometimes attached to grain, but it is not so with true parasites. But as most of these are cryptogamic plants, we will say a word in regard to the mode of reproduc tion of these singular plants, before entering into details, in order to make the following explanations intelligible to the reader.

Botanists divide vegetables into two great classes, viz: those in which the organs of reproduction are visible or apparent, which they call phanerogamic, and those in which these organs do not appear and seem not to exist, which they call cryptogamic. For a long time the reproductive processes of several families of these latter, such as the uredines, mucedines, &c., was unknown; there was even a hesitation in deciding as to several individuals of these families whether they belonged to the vegetable kingdom even. But since the invention of convex glasses, and the attentive studies of the learned physiologist, Benedict Prevost, it can no longer be doubted that the moulds, the rusts of plants, &c., are real vegetables, which, although they do not conform entirely like others, yet do not the less follow the same general rules of birth, growth, and death, and of reproduction by seeds. And from the point of view of a philosophic study

of nature, the mould which is cut with the edge of the knife in opening a loaf of bread, which is a little stale, while showing its roots, stems and branches, its flowers, and grains, productions which could not have come into being except from a seed which has resisted the action of fermentation in the dough, and the heat of the oven, does not any less announce to you the supreme artist, than those beautiful productions which make the charm of the fields and the beauty of the garden.

If the dust of caries or any other uredo be spread upon the surface of water, maintained at a temperature of 10 or 12 Reaumur (55° to 60 Fahrenheit), each globule of the dust will be seen at the end of a few days, swelled to double its previous diameter, and then sprouting a tubercle five or six times as long as it is in diameter. This tubercle then divides at its extremity, into six, eight, or even ten branches, sometimes sessile and sometimes ramified. These branches still later present apparent articulations, or rather internal grains infinitely small, and at the same time the globules will appear withered and show reticulations, which without doubt previously contained the grains or sporules now developed, and which we cannot refuse to regard as the seeds of the plant. The globules, then, which form the caries, rust, &c., of plants, are cryptogamic plants half grown, and which must be placed in other circumstances to complete their development. This being established, we will occupy ourselves with a separate consideration of caries, smut, and rust, the only parasitic plants recognized as injurious to grain.

To the foregoing concise description of parasites we will add, as a curious example of animal parasites, the following description of "Rust in Oats," not because of its being the appropriate place for considering this branch of the subject, but merely to give an example of the second class of these enemies to the farmer and destroyers of his labors.

RUST IN OATS-WHAT IS IT?-Throughout the whole southwestern portion of the Union, the oat crop has suffered from a terrible blight, which from its resemblance to the fungus substance that sometimes attacks wheat by that name, has been called rust. So far as we are informed, rust in oats has hitherto been unknown. We have never heard or read of anything of the kind, in any section of the country. The fact that it is thus unusual opens a wide and interesting field to the naturalist, and in this case to the entomologist, as it invites investigation in a channel, so far as we can ascertain, heretofore unexplored.

While in West Tennessee, a short time since, we took occasion to examine the blade of the oat under a microscope (kindly furnished us by a friend), and were greatly surprised with the phenomenon which

the glass revealed. Since then we have followed up those examinations, by the aid of more powerful instruments, at the Medical College in this city, in company with several scientific gentlemen, among whom were Drs. Briggs and Buchanan, of the medical faculty.

The cause of all this destruction of the oat crop is a living worm, too small to be plainly seen with the naked eye. A single blade or leaf of the oat sometimes contains hundreds of them. They lie encased in the tissues of the leaf or blade, where they have been germinated, beneath the epidermis or thin pellicle over the exterior portion of the blade, and, as they progress in development, the skin of the leaf is raised into curious puffy blisters. The growth of the. worm subsequently ruptures these, and it escapes to feed on the plant. When first released from their covering, they are of a beautiful, clear, red color, almost transparent, but soon begin to change color and form, getting more opaque and dark in appearance until, in the course of transformation, they become a black bug, with legs and wings, when they attack the head or grain of the oats.

Under the microscope, the dust which remains on the leaf closely resembles that on the wings of butterflies.

How this innumerable army of infinitesimal worms originated is yet a mystery. It is a singular fact, however, that wherever the greatest quantity of rain has fallen, there the oat crop has fared the worst. In our recent trip through West Tennessee, we saw but a single field of oats, between the Mississippi and Tennessee rivers, which was not a failure, or into which it would not be folly to put a scythe-blade. That field was near Denmark, in Madison county, and was sown very early. It is well known that more rain has fallen in West Tennessee this season than in any other part of the State; hence the extreme wet weather must have had some agency in the production of this animalcule. It is also well known that moisture and heat will produce and multiply animal life, millions per hour, and therein we judge is the secret of this destruction of the oat crop. It is one of those cases of natural phenomena which occur only at a certain stage in the growth of plants, and under peculiar states of temperature and weather. It may happen next season, or it may not occur again for many seasons.-Southern Homestead.

VEGETABLE PARASITES--We will now direct, attention to that class of parasites which are of vegetable nature, and which are particularly noxious to the ceralia which are objects of cultivation. These parasites are all minute plants of the cryptogamic class, and are mostly microscopic, being in their individual magnitude so minute as to escape the scrutiny of the unassisted eye, but are yet in a state of aggregation not only discern