1853.] 437 
movement lowered it in both tubes. Expiratory movement caused it to rise in 
both. 
During numerous vivisections, I noted the following corroborative facts :— 
The lung grows pallid in extreme inspiration, it flushes to a deep red in expi- 
ration. That this change of color is not due to a mere aggregation of the capil- 
laries, is clear from the following fact. During complete inspiration the lung 
was scratchéd so as to opensome capillary vessels. No bleeding occurred until 
the lung was allowed to contract, when the wound began to ooze. ‘The flow of 
blood was greatest in complete expiration. Care must be taken not to wound 
any large vessel. The illustrative bearing of these facts upon my preceding re- 
marks is too plain for further comment. 
At the moment of complete inspiration. the capillary circulation is retarded 
or checked. As a consequence there is an accumulation of blood in the pulmo- 
nary artery and right heart, and a deficiency of blood in the pulmonary vein and 
left heart. © 
Owing to this double disturbance, the heart beats slowly. The same set of 
causes, produced in another way, lessen the heart beats in one of the stages of 
asphyxia. ‘This view is also supported in other ways, and by certain facts too 
numerous for mention here. 
In expiratory fixation the heart quickens as I have very amply proved. 
This is due to several causes :— 
1. In expiration, however complete, the lung still contains enough of air to keep 
its vesicles moderately open. Therefore the blood traverses its tissue with ease, 
until asphyxia ensues. 
2. The muscular exertion requisite for a complete expiration is one-third 
greater than that which a full inspiration demands, and as we well know mus- 
cular exertion quickens the pulse. 
3. Owing to this excess of expiratory force, and to the firm pressure ex- 
erted by the condensed lungs upon the heart, that organ is mechanically stimu- 
lated. Ifthe heart of an animal be grasped during life it will flutter under the 
hand with a quick beat, and as if shuddering beneath the compressing agency. 
If the lung itself is firmly and equally pressed against the heart the same result 
occurs. 
To the combined influence of the three causes above enumerated, I ascribe the 
rapid pulse of fixed expiration. I have therefore shown that in the movements 
of respiration, as wellas in states of extreme inspiratory and expiratory fixation, 
the pulmonary circulation is subjected to singular and interesting modifications. 
I shall close my remarks with a single application. 
‘During inspiration the lungs contain a maximum amount of blood which is to 
some degree retarded in the capillaries at the moment of inspiratory fulness. It 
is precisely at this moment that the lungs contain most oxygen. On the other 
hand, during expiration, and during expiratory fixation, the erated blood, leaves 
the lung with the utmost facility. A regulation so beautiful as this should not 
be allowed to escape attention. For other and equally curious deductions I re- 
fer to the essay itself. 
The Report of the Corresponding Secretary was read and adopted. 
ELECTION. 
The Rey. Joseph H. Wythes was elected a Member of the Academy. 
December 6th. 
Vice-President BripGEs in the Chair. 
Letters were read— 
From the Zoological and Botanical Socicty of Vienna, dated 21st 
Aug., 1858, transmitting vols. 1 and 2 of their Transactions. 
From the Royal Bavarian Academy of Sciences, dated Nov. 6, 1858, 
