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 scratched so as to open some 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 : 



l.In expiration, however complete, the lung still containsenough 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. If the 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 well as 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 aerated 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 Rev. Joseph H. Wjthes was elected a Memler of the Academy. 



December 6tJi. 

 Vice-President Bridges in the Chair. 



Letters were read 



From the Zoological and Botanical Society of Yieniia, dated 21st 

 Aug., 1853, transmitting vols. 1 and 2 of their Transactions. 



From the Royal Bavarian Academy of Sciences, dated Nov. 6; 1853, 



