Disease, is that condition of the body, in which it has declined from a state of health, so that its different functions are either greatly impeded, or performed with difficulty.
Of all organized creatures, man is subject to the greatest diversity of diseases : some impairing only the use of the part immediately affected; for instance, the palsy, gout, rheumatism, etc.; others dis-ordering the whole body, such as fever, apoplexy, etc.; again others disturbing the mind, as delirium, melancholy, and the like; and lastly, some attack both mind and body, such as phrenzy, accompanied with fever.
Without perplexing the reader with conjectures on the origin and propagation of diseases, we may observe, that in proportion as men associate together in large and populous places, their manners and habits become more refined; while they gradually degenerate in bodily strength, and energy of mind, so that they are less capable of resisting the noxious agency of the elements, and other external powers. This progress towards refinement is always attended with an increase of luxury, the painful effects of which are sooner or later experienced by its votaries. Luxury, indeed, has also afforded the means of lessening the sudden influence of cold, heat, rain, moisture, and other external causes; for we can occasionally guard against their severity; but, on their next return, we are liable to be acted upon with additional vehemence. To this state of things we owe the intro-duction of many articles, both of food and dress, the consequences of which too frequently prove to bo injurious to our bodily welfare. Thus it may be safely affirmed, that the number and variety of diseases, in a great measure depend upon the prevailing refinements in the extensive-department of luxury The passions are another fruitful source of disorders. Man is per-haps more violently attacked, and more obstinately governed, by them than any other creature. These emotions variously affect the human body: the most hurtful and oppressive of them, however are terror and grief; the former in particular is often attended with the most fatal effects. The remedies to which we resort during the prevalence of passion, too frequently lay the foundation of lingering disorders both mental and corporeal, in which medicine can afford but precarious relief.
The last source of diseases to which we shall allude, is a variety of specific! contagions ; the greater part of which is probably generated in the atmosphere. Such is particularly the case with respect: to air that is vitiated by putrid, marshy, or noxious vapours, and by the unwholesome effuvia of various manuring processes, especially those of combustion, fermentation, and putrefaction. Lastly, there is another and very numerous class of contagious maladies, that perpetually migrate from one individual to another, such as the small-pox, measles, hooping-cough, iniluenza, putrid fevers, etc. of which we shall treat in their alphabetical places. - See also Contagion InFection.
Every disease weakens the digestive powers. The diet ought therefore in all cases to be light and easy of digestion. Paying due attention to this circumstance alone, without having recourse to those pernicious nostrums and pretended specifics, now in general circula(ion, will in a very great measure contribute to the recovery of the •patient. Medicines are doubtless of considerable utility, what properly and opportunely administered; but an indiscriminate use of drugs (such as prevails among the rant and fanciful), cannot fail to be productive of the the worst consequences. See . Chronical Diseases, vol. i. p. 521, and foll. Diseases of Plants are divided by Tournefort into the following ones : 1. Those which arise from too great an abundance of sap; 2. From having too little ; 3. From its bad qualities ; 4. From its unequal distribution ; and 5. From external accidents.
An abundance of sap causes plants to vegetate so luxuriantly, that they seldom arrive at the requisite degree of perfection. Wheat is in some climates subject to a disease of this nature, in consequence of excessive vegetation, without producing ripe grain. Such a delect may likewise be artificially induced, by planting any species of corn in too rich a soil: - toe much rain will be attended with a similar effect. When a vegetable is supplied too abundantly with juices, it is very apt to rot; one part of it overshadowing the other, so as to prevent the access of fresh air, for want of which it prematurely undergoes putreiaction. In grasses, however (fescue excepted), or in any herbaceous plant, too great luxuriance, so far from being a disease, is a very desirable property. According to Dr. Home ("Prin ciphs of Agriculture and vegeta-tion") dung is a great preventive of disease, arising from abundant moisture. The want of nourish-ment in plants may be easily ascertained by their decay ; in which case the only remedy is, to remove-from their vicinity such vegetables (and particularly weeds), as impede the growth of those we are desirous to cultivate.
The bad qualities, or unequal distribution of the juices of plants, occasion but few diseases which affect vegetables in this country, so that they are principally liable to external accidents, especially to the depredations of insects, such as snails, caterpillars, grubs and flies, to which we refer. - See also Beetle, Chafer, Crab, and Corn-fly.
The diseases which our gardeners chiefly observe, are :
2. Blasting of the. buds, occasioned by a frost happening while the leaves and blossoms are wet; in consequence of which the pores are contracted, and the vital juices obstructed : thus, if the sun begins to shine suddenly, they turn yellow, producing round fiery specks, whence frequently proceed tumors somewhat similar to warts, which rot, and generate maggots. Mr. Mortimer adds, that the want of rain, during the blossoming time, often disposes the blossoms to drop, from a deficiency of sap; to prevent which, he recommends frequent watering.
3. Blight ;
4. Mildew ;
5. Moss; to which articles we refer.
0. Rotten roots; an incurable disease, occasioned by setting the plants too deep.
8. Falling of the leaves, caused by the trees sprouting too early, or when they are attacked by too sudden heat or cold.
9. The Scurf or Leprosy, a disease which is confined to the bark, and is produced by excessive dila-tation of the pores, through which too great a proportion of perspirable matter exudes ; so that by adhering to, and hardening on the bark, it causes the latter to chap and crack, while it obstructs all perspiration. . Thus, the viscous rind or skin furnishes a secure retreat for vermin, which live both on the bark and on the tree.
To the various dieases should be added the injury done to trees by deer, hares, and rabbits, barking them. The best defence against the first of those animals, is to pale them round, or to paint the lowet part of the tree; but the former method is preferable. Hares and rabbits may be kept off by tying bands of straw round the trunk of every tree, as far as they can reach. Some persons make use of a composition of tar and lime, which certainly is not less injurious to the growth of trees than the depredations of hares or rabbits. In ge-neral, where any defence is requisite, straw-bands afford a tolerable security.