with but little opposition until 1854, when Wintrich, after a series of experiments, arrived at conclusions directly opposed to those of Williams and Longet in regard to the contractility of the muscular fibres of the bronchi, and refused to accept the spasm theory on the ground that it afforded no rational explanation of the phenomena of asthma. He believed that the various symptoms of that disease were due to tonic spasm either of the diaphragm alone or of the diaphragm and the other muscles of respiration. These experiments of Wintrich were so carefully conducted, and his standing as a specialist in respiratory diseases so high, that his theory found many supporters, and might perhaps have been generally accepted had it not been for the distinguished French physiologist, Paul Bert, who in 1870, with improved methods of scientific research, succeeded in demonstrating that Williams and Longet were after all correct in their statements as to the contractility of the bronchial muscles. One of the most zealous advocates of the spasm theory of asthma, and at the same time its most learned expositor, is Biermer,[13] whose classical lecture on that disease, which appeared a short time after the publication of Bert's experiments, is perhaps the most satisfactory work ever published on the subject. He defines bronchial asthma as a "neurosis depending upon tonic spasm of the bronchial muscles and caused by faulty innervation of the pneumogastric nerve." He claims that this theory is confirmed by clinical experience--that the suddenness with which the attack comes and disappears, and the long and forced expiration with the sibilant râles and other evidences of stenosis which accompany it, admit of no other explanation. In support of this view he calls attention to the rapidity with which the paroxysm yields to chloral, all of its symptoms disappearing within from five to ten minutes after the administration of a moderate dose of that agent. Wintrich and his supporters, besides denying the contractility of the bronchial muscles, object to the spasm theory that the distension of the thorax and descent of the diaphragm, both constant symptoms, are incompatible with spasmodic closure of the bronchial tubes, and that constriction from such cause by impeding the entrance of air into the alveolæ would be more likely to cause diminution in the size of the thorax than its enlargement, and that the diaphragm, instead of descending, would be drawn upward. Biermer acknowledges that this to a certain extent is true, and concedes that constriction of the tubes would interfere with both acts of respiration, but claims that it does not do so {195} to the same extent in the two movements. The spasmodic constriction acts as a sphincter which is readily overcome during inspiration, but prevents the escape of air during expiration, the latter movement being slower and less complete than the former. Were