NATURE AND CAUSATION. 611 



very difterent states, through the apparent similarity of their 

 general symptoms, has been rendered easier by the circum- 

 stance that the spasmodic affection, ' asthma,' is not un- 

 frequently prolonged into, or terminates in, that of the 

 paralytic condition of the air-tubes and associated lung- 

 structure which we call 'broken-wind;' also that this latter 

 and persistent state may at any time be aggravated by an 

 onset of a further attack of the spasmodic affection, extending 

 to other and additional bronchial muscular structures. 



The agents or mfluences which seem to operate in the pro- 

 duction of asthma are very similar to those which are credited 

 with the induction of the disturbance recognised as broken - 

 wind ; the chief of these are heredity, direct, and reflected nerve 

 irritation. In many instances these operating agencies seem 

 more occult in the spasmodic affection, and, when existing, less 

 under the influence of treatment. In many I have believed 

 them to be intimately dependent on fatigue and overwork, 

 when in an unfit condition from debility or previously existing 

 disturbance. 



Symptoms. — These are sudden in their development, distress- 

 ing while they last, and uncertain in their duration. The 

 dyspnoea, which is of a spasmodic character, so far resembles 

 that of broken-wind that the inspiration is accomplished with 

 greater freedom than the expiration, which is usually carried 

 through in a jerking manner, with a less marked double action 

 than in the latter affection. There is also here a more dis- 

 tinctly wheezing noise during the performance of the res- 

 piratory act, greater anxiety of expression, and exhaustion, with 

 less cough, which, when emitted, is not so soft or hollow, but 

 rather short, quick, and suppressed. The peculiar wheezing is 

 very distinctly detected in auscultating both the anterior and 

 lateral parts of the chest ; and if emjDhj^sema is present, per- 

 cussion may give an increased resonance. The more distinct 

 or individual features are the suddenness of the appearance of 

 the symptoms, their true spasmodic character, their marked 

 accessions or declme in the same animal over a very short 

 period of time, their severity, and their equally unaccountable 

 disappearance. 



"When fully developed the constitutional disturbance is con- 

 siderable, and the existence of fever, as indicated by the 



