Dust of various kinds, the pollen of plants, certain vapors, gases, smoke, and the emanations from many species of animals, have all been known to excite attacks of asthma. Some persons are so sensitive that the simple act of brushing their clothes is sufficient to bring on a paroxysm. Others are unable to inhale the perfume of roses, lilies, heliotropes, and many other flowers without suffering with an attack. The dust of hay will often cause paroxysms even in those who are not hay-fever subjects. Since Cullen first published the case of an apothecary's wife who had asthma whenever ipecac was powdered in her husband's shop numerous cases of a similar nature have {193} been recorded. Ramadge relates the case of an employé in the East India Company who was compelled to relinquish a lucrative appointment because the smell of tea always provoked a paroxysm of asthma. Many persons are unable to come into close proximity with horses, rabbits, cats, and other animals without suffering, and Austin Flint of New York experienced great inconvenience when absent from home from sleeping upon feather pillows. In his case the asthmatic attack was not brought on by all pillows, but what it was that made one kind more active than another he was unable to determine. In persons predisposed to bronchial asthma the eating of any indigestible substance may of itself be sufficient to cause an attack, and even an ordinarily full meal, if partaken of late in the day, may have the same effect. Dyspepsia in its various forms and the presence of irritating substances in the intestinal canal are such frequent causes of asthma that they have led to the establishment of several special varieties of the disease--_e.g._ a. dyspepticum, a. verminosum. Asthma is frequently due to uterine and ovarian disorders, the so-called a. uterinum. Voltolini of Breslau has described cases which were evidently due to the presence of naso-pharyngeal polypi, the attacks disappearing with their removal and reappearing with their renewed growth. These statements have been confirmed by subsequent cases observed by Haenisch. Attention has lately been directed to a number of cases in which the asthmatic paroxysm was found to be associated with catarrh of the naso-pharyngeal and laryngo-tracheal mucous membrane. In such cases it is thought that the irritation caused by the pressure of the swollen mucous membrane upon the adjacent nerves is conveyed through them to the pneumogastric, and thus provokes the bronchial spasm. Daly, Roe, Harrison Allen, Hack, and others have traced the paroxysms of hay asthma to an hypertrophied condition of the mucous membrane over the turbinate bones and septum of the nose, which renders it peculiarly susceptible to the action of the irritants which cause that troublesome affection, and have succeeded in curing many cases by simply removing the diseased tissue.