ESSENTIAL ASTHMA. $9 



In most cases the causes of asthma are as obscure as are those of 

 spasm of the glottis. Very rarely, lesions of the brain or pressure 

 upon the vagus by enlarged glands seem to cause it. More fre- 

 quently asthma appears as an evidence of reflex excitement, the 

 source of which lies in some remote part of the body, such as the 

 uterus. Indirect nervous irritation, mental agitation, the action of 

 tobacco, of ipecac, and of the aroma of certain flowers, have also 

 been known to bring on asthma. 



The relationship between catarrh and asthma still remains un- 

 explained. There are asthmatics who know that they will have an 

 attack whenever they catch cold. In many cases of bronchitis with 

 emphysema the dyspnoea, usually trifling, paroxysmally rises to the 

 level of a fit of asthma ; and many authorities do not hesitate to as- 

 sume the existence of a bronchial spasm due to intercurrent catarrh 

 of the bronchial mucous membrane. On the other hand, it is very 

 truthfully maintained that an asthmatic attack, which may begin 

 quite free from all sign of catarrh, may nevertheless end with a 

 catarrh ; so that it would seem as though the bronchitis were the 

 result of the asthma ; although it may be that, when the fit thus 

 begins without catarrh, it is preceded by a fluxionary swelling of 

 the mucous membrane of the smaller tubes, which may or may not 

 be followed by secretion at the height of the attack (JBiermer). 

 This alliance of hypersemia and secretion with asthma gives weight 

 to the newly-announced views of Weber in Halle, who believes that 

 the symptoms of asthma do not depend upon muscular spasm, but 

 that they may be more readily explained on the hypothesis of swell- 

 ing of the mucous membrane by dilatation of the blood-vessels as a 

 result of perturbed vaso-motor nervous influence, such as happens 

 in the nasal mucous membrane of many persons who have catarrh, 

 in whom one or both nostrils become stopped up. According to 

 Leyden, a peculiar expectoration has largely to do with one form 

 of asthma. This sputum is scanty, viscid, and opaque, containing 

 quantities of fine grayish filaments and flocculi, which come from 

 the finest bronchi. In these we find a great mass of delicate, pe- 

 culiar crystals of elongated, octahedral form, distinctly visible when 

 magnified three hundred to six hundred times. These crystals are 

 supposed to set up a mechanical or chemical irritation upon the tips 

 of the vagus, and thus to give rise to reflex muscular spasm of the 

 smaller bronchi. Further observation must teach us whether the 

 presence of these crystals found in the sputa of asthmatics is essen- 

 tial, or merely accidental, and whether (as has been asserted) they 

 are also found in the sputa of ordinary bronchitis. 



Another explanation of the cause of asthma has been attempt- 



