the higher or more perfect classes of animals, yet they certainly are satisfactory evidence that plants probably are nearly as sensient as the Zoophyte, or even as the Polypus and the Hirudo,— animals that may be cut into pieces, and each section become a perfect individual,-animals whose heads may be taken off and grafted upon other bodies,-animals that may be turned with their outsides inwards, and yet without any apparent inconvenience. If plants be endowed with sensation of the most limited degree, it explains the cause, throws light upon the prevention of many diseases that affect those which are the object of cultivation, warns the tiller of the soils from the late performance of many of his operations, and teaches him generally to be less violent in his field practice. If a grape vine be pruned too late in the spring, the bleeding, or effusion of sap, has been known to be so violent, that the tree has died from absolute exhaustion. Stone fruits, if severely wounded, are frequently destroyed by the inroads of a disease resembling in all its characteristics the cancerous affections of animals; and I have known a whole crop of wheat affected with a swelling of the stem or culm, evidently caused by an extravasation of the sap from its ruptured internal vessels, owing to the roller being passed over the crop when of a growth somewhat too forward.

After these prefatory remarks, intended to save from fundamental objection the opinion I entertain, that most, if not all the diseases of plants, are connected with or arising from causes affecting their vital power, -for these remarks exhibit facts and reasons establishing the existence of such power in plants,-I will now proceed to consider in detail, and illustrate by experiments, some of the most prevalent diseases of our cultivated plants.

*

The Curl. No disease appears to me so evidently to arise from impaired vital energy in the plant, as the curl that of late years has made such extensive ravages upon our potato crops. Any one can insure the occurrence of this disease, at least I have found so in the county of Essex, by keeping the sets in a situation favourable to their vegetation, as in a warm damp outhouse, and then rubbing off repeatedly the long shoots they have

The opinion of Mr Munro of Brechin nursery, coincides with mine. He considers "weakness is the cause" of the disease. See Gardener's Magazine, xi. 417.

thrown out. Sets that have been so treated, I have invariably found produce curled plants. Is not the reason very apparent ? The vital energy had been weakened by the repeated efforts to vegetate; so that, when planted in the soil, their energy was unequal to the perfect development of the parts; for the curl is nothing more or less than a distorted or incomplete formation of the foliage, preceded by an imperfect production of the fibrous

roots.

The following experiment I consider as very decisive: it was made in the year 1830, in my garden at Great Totham, in the county of Essex. The soil in this case, and in all others that will be stated hereafter, unless otherwise specified, is light, deep, moderately fertile, resting on a substratum of siliceous gravel, and is constituted as follows.

The variety employed in this experiment was the Early Shaw. An equal number of whole moderately-sized potatoes, that had been treated in three different modes, were planted the last week of March. No. 1. Twenty sets that had been carefully kept cold and dry throughout the winter, firm, unshrivelled, and with scarcely any symptoms of vegetation. No. 2. Twenty sets that had been kept warm and moist, and from which the shoots, after attaining a length of six inches, had been thrice removed. No. 3. Twenty sets which had been kept warm and moist for about half the time that No. 2 had, from which the shoots, three inches in length, had been removed only twice.

All the sets were planted the same morning, each exactly six inches below the surface, and each with an unsprouted eye upwards. The spring was genial.

Of No. 1, nineteen plants came up. The twentieth seemed

to have been removed by an accident. Of the nineteen, not one was curled. The produce a full average crop.

Of No. 2, all came up, but twelve days later than those of No. 1; and three of the plants sixteen days later. Fourteen of the plants were curled.

Of No. 3, all came up, but from ten to fourteen days later than No. 1. Four plants were as severely curled as those in No. 2, eight were less so, and the remainder not at all; but of these the produce was below an average, and a full fortnight later in ripening.

Dickson, Crichton, Knight, and others (Caledonian Hort. Mem., Horticultural Trans., Loudon's Gardeners' Mag., &c.), have found, that tubers, taken up before they are fully ripened, produce plants not so liable to the curl as those that have remained in the ground until completely perfected; and I believe, under ordinary treatment, this to be the fact, for it is rational. The process of ripening proceeds in the potato, as in the apple, after it has been gathered, and until that is perfected, it is accumulating vigour, shews no appetency to vegetate, consequently is not exhausting its vitality,—which is a great point, considering the careless mode usually adopted to store them through the winter,—for this energy commences its decline from the moment it begins to develop the parts of the future plant. Tubers taken from the soil before perfectly ripe, never are so early in shewing symptoms of vegetation. Crichton, Hunter, and Young, in some of the works before referred to, have also agreed, that exposing the sets to light and air, allowing them to become dry and shrivelled, also induces the curl in the plants arising from them. This result of experience also confirms my conclusion, that the disease arises from deficient vital energy; for no process, more than this drying one of exposure to the light and air, tends to take away from a tuber altogether the power of vegetating. A farmer, Mr G. Allaker, residing in the same village that I do, employed last year (1836) rather small sets: cutting a moderate-sized potato into at least two pieces. Unfavourable weather, other business, and a somewhat dilatory habit, caused him to leave those sets upon a barn floor, drying for more than a week. He planted with them a two-acre field, and not more than three-fifths vegetated, of which three-fifths, a fourth were in various degrees curled.

Similar results were obtained in the experiments of Mr Wright, a market gardener of Westfield. When the sets were allowed to ferment in a heap, allowed to sprout, &c., he had a crop, one-fifth of which was curled.-Gardeners Mag. x. 436.

Every one acquainted with the cultivation of the potato, is aware of the great difference existing in the varieties as to their early and rapid vegetation; those that excel in this quality, of course, are the most easily excitable. A consequence of this is, that they are always planted earliest in the spring, before their vital power has become very active; and of all crops, practice demonstrates these early ones are least liable to the curl. But what is the consequence, on the contrary, if an early variety is planted for a main crop later in the spring, when extraordinary pains in keeping them cold and dry have not been employed to check their vegetation, and consequent decrease of vital energy ? Such crops, then, more than any other, is liable to the disease.

The statements of a practical man in the Gardeners' Magazine, vol. x. 433, entirely support my views of the disease. He remarks, that, in 1826, through the prevalence of rain, the late crops of potatoes never sufficiently ripened so as to be marketable. They were reserved for planting next season, and the consequence was, that the curl affected the crops that year to a great extent; but those who planted well-ripened tubers had crops free from the disease, and as productive as usual. Now we all know that the vital energy is always the most powerful in a bulb or seed that is perfectly ripened.

The results of my view of the disease, sustained by numerous experiments, are, that it will never occur if the following points are attended to:-1st, That the sets are from tubers that exhibit scarcely any symptoms of incipient vegetation. To effect which, they ought, throughout the winter, to be preserved as cool, as dry, and as much excluded from the air as possible. 2dly, That the tubers should be perfectly ripened. 3dly, That they should be planted immediately after they are cut. 4thly, That the manure applied should be spread regularly, and mixed with the soil, and not along a trench in immediate contact with the sets. 5thly, That the crop is not raised for several successive years on the same area.

VOL. VIII.-NO. XYXVIII.

210

ON THE UNEQUAL DISTRIBUTION OF, AND UNEQUAL ASSESSMENT FOR PUBLIC BURDENS IN SCOTLAND.

MUCH importance is in this country attached to political reforms, to the improvement of our national institutions, and the extension or equal participation of civil privileges. But there is another kind of reform, which to all classes of the community is no less material, viz. financial reform, by which the burdens imposed on them for the support of the State, may be reduced and lightened.

There are two ways in which this last kind of reform may be effected. The one is by diminishing the amount of the public expenditure; the other is, by equalizing the burdens over all classes of society, according to their means of bearing them.

The first of these financial reforms has been already tried, and carried to a great extent. The amount of taxation, in consequence, has, within the last six or seven years, been reduced by many millions;-whereby additional elasticity and energy has been given to capital and industry in almost every quarter. There is, however, a limit to retrenchment in the public expenditure, which some think has been already reached if not overstepped, and which at all events, it will be allowed, cannot be far distant. But there remains still the other plan of relief, by which, though the weight of taxation is not lessened, it is equally distributed over the body politic in such a way, that no one class bears more than its due proportion. The advantage of such an adjustment of taxation is perfectly obvious. The prosperity of a country depends chiefly on its capital and industry being allowed to flow freely into every channel; and this object cannot be attained, unless the pressure of taxation be laid on each class according to its capability to bear it. Adam Smith states it as the first and most essential maxim of taxation, that "the subjects of every state ought to contribute towards the support of the government as nearly as possible in proportion to their respective abilities; that is in proportion to the revenue which they respectively enjoy under the protection of the state. The expense of government to the individuals of a great nation is like the expense of management to the joint tenants of a great estate,"