418 
R. B. PLACEMAN 
1 think the true pathology of pulmonary emphysema may 
be traced to asthma, which is a spasmodic contraction of the 
bronchial tubes, which so much impedes the ingress and egress 
of air in respiratory forces to effect it. 1 am aware that many 
will be opposed to the daring assertion that the bronchial 
tubes do really possess muscularity and are not merely elastic 
tubes, and are the seat of spasmodic contraction, experiments 
having shown that under the influence of a galvanic or chem¬ 
ical stimulus the circular fibres of the bronchi contract 
readily but slowly; this contractibility extends only to the large 
bronchi, the finer ones have no peristaltic or vermicular mo¬ 
tion, and the expulsion of mucous and other fluids from the 
bronchial tree, besides the ciliary motion, is the increasing 
velocity with which the air in expiration passes from the pul¬ 
monary cells to the narrow converging bronchi. 
The air in entering the lungs passes with decreasing veloc¬ 
ity as it spreads out in the minute tubes and cells, the com¬ 
bined area of which greatly exceeds that of the larger branches. 
In expiration this is reversed, the motion is more rapid and 
forcible as it converges towards the trachea and glottis, when 
the process is brought to its consummation in special efforts 
at coughing. 
The subject of this paper was a little pony suffering from 
chronic emphysema of the lungs in a very aggravated form 
and recommended to be destroyed by several veterinar}^ sur¬ 
geons. 1 asked the owner to send me the pony for experiment¬ 
al purposes, in the course of which experiments 1 discovered 
that bronchial contractibility was influenced differently by 
various medicinal agents. 
Thus hydrocyanic acid did not impair it at all, opium 
and morphia very little, aconite a little more, but belladonna 
almost destroyed it. 
To return to emphysema of the lungs, it is a result of 
spasmodic asthma, which there is no reason to doubt is due 
to a tonic spasm of the muscular fibres of the bronchi and 
construction of these tubes, and this spasm is due to reflex 
action of the nervous system ; for instance, irritation of the 
stomach by coarse and indigestible food, and we all know 
