There are three species of Asthma;

1. Asthma Spontaneum, when without any manifest cause.

2. Asthma Plethoricum, when it arises from plethora.

3. Asthma Exanthematicum, originating from the repulsion of some acrid humour.

Asthma rarely appears before the age of puberty, and seems to attack men more frequently than women, particularly those of a full habit, in whom it never fails, by frequent repetition, to occasion some degree of emaciation. In some instances, it arises from an hereditary pre-disposition, and in many others it seems to depend upon a particular constitution of the lungs. Dyspepsia always prevails, and appears to be a very prominent feature in the pre-disposition. Its attacks are most frequent during the heats of summer, in the dog-days, and in general commence about midnight. On the evening preceding an attack of asthma, the spirits are often much affected, and the person experiences a sense of fulness about the stomach, with lassitude, drowsiness, and a pain in the head. On the approach of the succeeding evening, he perceives a sense of tightness and stricture across the breast, and a sense of straitness in the lungs, impeding respiration. The difficulty of breathing continuing to increase for some length of time, both inspiration and expiration are performed slowly, and with a wheezing noise; the speech becomes difficult and uneasy, a propensity to coughing succeeds, and the patient can no longer remain in a horizontal position, being as it were, threatened with immediate suffocation.

These symptoms usually continue till towards the approach of morning, and then a remission commonly takes place; the breathing becomes less laborious and more full, and the person speaks and coughs with greater ease. If the cough is attended with an expectoration of mucus, he experiences much relief, and soon falls asleep. When he awakes in the morning, he still feels some degree of tightness across his breast, although his breathing is probably more free and easy, find he cannot bear the least motion, without rendering this more difficult and uneasy; neither can he continue in bed, unless his head and shoulders are raised to a considerable height. Towards the evening, he again becomes drowsy, is much troubled with flatulency in the stomach, and perceives a return of the difficulty of breathing, which continues to increase gradually, till it becomes as violent as on the night before. After some nights passed in this way, the fits at length moderate, and suffer more considerable remissions, particularly when they arc attended by a copious expectoration in the mornings, and this continues, from time to time, throughout the day; and the disease going off at last, the patient enjoys his usual rest by night, without farther disturbance.

The pulse is not necessarily affected in this disease, though often quickened by the difficulty of breathing. In plethoric habits, the countenance is flushed and tinged during the fit; but in others, rather pale and shrunk; in the former too, some difficulty of breathing and wheezing usually remain in the interval; in others, the recovery is more complete. On this is founded the common distinction of asthma into the humid, pituitous, or catarrhal, and the dry, spasmodic, or nervous forms. The exciting causes are various: - accumulation of blood, or viscid mucus in the lungs, noxious vapours, a cold and foggy atmosphere, or a close hot air, the repulsion of eruptions, or other metastatic diseases, flatulence, accumulated faeces, violent passion, organic diseases in the thoracic viscera, etc. Sometimes the fits return at pretty regular periods; and it is generally difficult to obviate future attacks, when it has once occurred; but it often continues to recur for many years, and seldom proves fatal, except as inducing hydrothorax, phthisis, etc.

The treatment of this disease by the faculty varies materially, and is guided in general by the nature of its appearance, and in young persons of plethoric habits, the abstraction of blood is successfully resorted to. In ambiguous cases cupping is preferable, or leeches to the chest, with blisters. Mild cathartics are also serviceably employed. Nauseating emetics have been found of great use. Squill combined with ipecacuanha, opium, fetid gum resins, smoking and chewing tobacco, strong coffee, and various other things, compounds and simples, are administered with effect at times; but much depends on the age and disposition of the patient, and more on the atmosphere as to temperature, drynesss, purity, etc. The regimen of course is a material point, and must be paid the most rigid attention to, in all stages of the disease.