"Such means," he observes at page 46, "cannot impart to the tubers full vigour, and still less the longevity that is acquired from a renewal of the variety from seed. It will only be efficacious for a year or two. But even this much gained, in the present state and prospect of the potato, is a triumph. When the seed is separated from the ground, great care must be taken to preserve the sap and prevent exhaustion; green tubers being more precarious to preserve than those that have been fully ripened. The earth, however, will preserve them fresh and sound. Not one is known to rot when left in the ground. No matter at what time they are parted from the parent stalk; they all spring vigorously when the natural season arrives, and not until then."

This fact suggests to our author the plan to be adopted for keeping potatces in winter.

"The nearest approach,” he continues, "that in pitting you make to their natural bed, the greater the certainty of preservation. Keeping this injunction in view, I recommend the following plan :

“Prepare a pit in a situation free from the possibility of retaining bottom water. Sink it a foot deep, if the soil will admit. The width may be from three to four feet. Spread a layer of potatoes along the bottom not deeper than four or five inches. Then throw over them a stratum of the dry wellbroken mould, taken from the pit. Then lay another layer of potatoes of the same depth, and more earth, as formerly. Add a third layer of potatoes, and finish with a gently rounded, not a ridged top, as usual; and, still retaining the rounded shape, cover eight inches of earth over the whole. Cut a trench along both sides of the pit to carry off water. Be sure to have loose earth nearest the potatoes, and allow as much of it as possible to mingle with them. Take care that they be dry when so stored, and that there be no wet earth adhering to them, as potatoes laid past in a wet state never keep well. Use no straw on the top, as I wish the earth above the potatoes to know the changes of weather,—to receive damp or drought alternately, in order that, as near as possible, their bed may resemble that in which they grew. I hope my object in the above specified plan will be discernible by every person. Under the ordinary pit or house method of preserving, potatoes begin to grow very early in spring; and when once growth has fairly commenced, they become hot in the close body that is formed by the daily increasing fibres; the growth is more hastened, the heat being more confined by the thick mat of straw which lies betwixt them and the top earth; which earth would otherwise in a great measure extract the internal heat, were any such engendered."

Testing the vitality of the potato sets before planting, is urged by Mr Aitken as an important consideration. This is his method, which, if generally pursued, would obviate the necessity of early planting, and permit time to work and clean the land:

"Select a piece of dry ground," says Mr Aitken, at p. 53, "in a securely fenced place; when required on a large scale, as will be the case on extensive farms, lay

the ground off in beds of five feet wide, with alleys of two feet. Use a garden line, and lay them off in a neat manner. From the alleys take earth to cover the surface of the beds, taking care to raise them a little in the middle. This done, have in readiness, and placed conveniently to the beds, a quantity of fine compost earth, consisting of one-third of moss, one-third of clean earth, one-third of peat or coal ashes, mingled with a small proportion of lime, enriched by urine, or pourings from a dunghil. The beds and compost being both in readiness, cut all the seed potatoes which are above the size of a common hen's egg. By the first cut, take off about the fourth part at the root end, and lay it aside for food. Next, divide the top end into pretty large cuts, the small ones use entire, either kept by themselves, or mixed with the cuts. When a quantity is thus cut, spread it over the bed, upon which previously is to be laid a thin covering of the compost. I would recommend the layer of potatoes not tu consist of more than two cuts in depth, spread over with an inch of compost. This done, if the weather be dry, take a watering-pan and water most effectually, in order to wash the compost into the bed amongst the cuts; the quantity of water being regulated by the state of the weather. After this, give them another covering of compost, in all about three inches in depth. In this manner proceed until as many are so laid down as will be required for the farm. Farther watering will only be necessary if the weather is dry. After the cuttings have lain in the seed-beds some time, it will be necessary to examine them to see if they are springing, of which there can be little doubt. If any doubts are entertained, however, it will be necessary to prepare more sets, and put them in fresh beds, to insure a sufficiency at the time of transplanting. The chance of the seed springing in the beds is ten to one compared with the ordinary way. Here, should the weather be dry, abundance of moisture can be communicated at any time; and, in place of a parched soil robbing the sets of moisture till they are quite shrivelled, as was the case during the intense drought of last May, the sets will be duly fed and nourished from the fat juices of the rich compost. Allow them to remain in the bed till the shoots come above ground. If the compost has been mixed with lime, as directed, it will act as a powerful stimulant upon the weakened and exhausted vegetative powers of the potato, and very much accelerate and strengthen the young shoots. If this has been neglected, it may still be partially accomplished, either by dusting powdered lime among the cuts, or mixing it in the water. If no compost has been prepared, good clean loose earth will answer the purpose, but it would not be equal in efficacy to a rich well-prepared compost."

After thus describing the manner of testing the seed, Mr Aitken gives minute directions for conducting the field operations in the preparative planting, and for setting the tested seed. The Dumbartonshire Farmer has also a test for discovering the decayable from the undecayable cut sets of the potato. Thus:

"From the now generally diseased state of the potato, it appears to us that there is but one way to test the seed before planting, which, if properly attended to, will prevent those melancholy results that may be anticipated in the crop. It is this: Select from the potatoes proposed for seed a dozen or

two; cut them with a sharp knife into sets; then put them on the floor of a potato-house, or any other place free of damp, with the skin next the floor; if, upon examining them. three or four days after, it will be found that the incision has dried up, and be covered with a kind of new skin, be assured that the seed is wholesome—plant it; but if, on the contrary, the wound is found to be wet, sluggish, and spotted-touch not the unclean thing, but be certain that the constitution of the potato is exhausted. This experiment should not be tried until vegetation has completely taken place, say about the middle of April."-p. 16.

We shall not accompany Mr Aitken into the comparative merits of cut and whole seed, the raising of early potatoes in the fields, or the method of raising new varieties from the seed to secure the renovation of the potato, all which subjects will amply repay perusal ; but only intimate that the appendix contains the remarks of Mr Aitken on the papers on the potato failure which has appeared in the Highland Society's Transactions, and elsewhere. We say to all potato cultivators, "Read, mark, learn, and inwardly digest," Mr Aitken's little work, for your own sakes.

ACCOUNT OF THE INSECTS MOST INJURIOUS TO VEGETABLES AND ANIMALS, AND OF THE MEANS BEST CALCULATED TO COUNTERACT THEIR RAVAGES. NO. I.

By JAMES DUNCAN, M.W.S., &c.

Quæ et quantum noceant insecta exquirere adgressus sum, ut civium forte meorum aliique inde intelligant et discant, quantæ sit necessitatis ea rite noscere, tum ad Dei in nobis augendum timorem atque reverentiam, cui tam fortes tremendæque in promptu sunt copiæ, quibus sui apud nos oblivionem debellet; tum ad ea præcavenda incommoda, quæ nostræ alias negligentiæ jure meritoque tribuerentur.-Linn. Aman. Acad. iii. p. 338.

WHEN it is considered that the number of insect species inhabiting Britain is between ten and eleven thousand, that the individuals constituting these species exceed in most cases all calculation, and that the proportion of about one-half subsists entirely on vegetable substances, it becomes obvious that the aggregate amount of damage they occasion to the latter must be very considerable. Many, it is true, derive their sustenance,

from plants of no direct utility to man, while in other instances, where this is not the case, the injury committed is so slight as scarcely to deserve consideration; and although these deserve to be studied for the purpose of observing their structure, ways, and instincts—always curious and interesting subjects of inquiry -they do not call for attention in any other view. But the case is very different with such as attack the plants to which we are chiefly indebted for our food, or which form the principal support of our domestic animals. The extent to which this takes place is unhappily a matter of daily observation. There is scarcely one of our most useful plants which is not assailed in one way or other; and the forms of insects and their modes of living are so infinitely diversified, as to enable them to continue their depredations in all the different states of these plants. The various kinds of corn, for example, have a host of enemies in the subterraneous larvæ of beetles, which consume the roots; various kinds of caterpillars feed on the blade; some particular species attack the ear; and, even when laid up in apparent security, a small beetle is often found to scoop out the interior of each grain, and convert it into an abode for itself. The turnip, in like manner, is equally exposed to these depredators. If the seed of this useful plant escape the attack of a minute weevil, another enemy awaits the unfolding of the cotyledon leaves, and a third buries itself in the bulb and rootlets, which become diseased and covered with unseemly excrescences; while the mature foliage is often consumed by caterpillars, as was exemplified to a considerable extent last summer. Many plants have a particular insect appropriated to them; others, as in the examples mentioned, form the food of several different kinds; and when it happens, from some mysterious cause which we are at present unable to penetrate, that these creatures suddenly increase beyond their due proportion, the partial or entire destruction of some of our most valuable crops is occasionally effected by their agency.

But even when there is no remarkable augmentation of their numbers, there is reason to believe that the injury occasioned to vegetation by insects is at all times greater than is generally supposed. Their operations are often carried on under cover, cither beneath the surface of the soil, within the substance of the plant,

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or in other situations where they escape observation. Many kinds, again, feed only in the night, and conceal themselves during the day in holes and crevices. In consequence of this latent and insidious mode of attack, there is no doubt that we are often led to ascribe the unhealthiness and decay of plants to badness of soil, unfavourable weather, and other causes, when in reality they are produced entirely by insects. The attention of gardeners and agriculturists, moreover, is seldom directed to their depredations, unless when these become so extensive as to threaten serious injury to their crops; but it is obvious that they must be carried on to a greater or less extent every season, for the existence, at least, of the respective species is always maintained, and this can only take place at the expense of the plants on which they are destined to feed. Whether, therefore, they fall under our observation or not, there is always a host of minute depredators at work, which, in the instinctive prosecution of their own habits and economy, interfere in no inconsiderable degree with the interests of the agriculturist, by preventing the full return which many of his crops would otherwise produce.

In these circumstances it becomes a matter of some importance to inquire into the means which seem best calculated to secure our useful vegetables against the injuries arising from this cause. It may be affirmed that very few efficient remedies have hitherto been discovered; and it generally happens, when noxious insects appear in unusual profusion, that they must either be allowed to ravage our crops unmolested, or if they can be checked at all, it is at a trouble and expense disproportionate to the advantage sought. The only course which is likely to lead to the discovery of proper remedies, is to investigate carefully the habits and natural history of the respective species of insects, in connection with the structure and general physiology of the plants which they attack. In prosecuting this object, the attention should be directed to ascertain the time when, and the manner in which, the eggs are deposited, as well as their composition, and the consistency of the enclosing membrane, with a view to determine in what way the vital principle might be most easily destroyed; for there seems reason to believe that this may occasionally be effected simply by sprinkling them with