1853.] 435 



Kovemher 22d. 

 Mr. OrD; Presidentj in the Chair. 



Letters were read 



From the Historical Society of Pennsylvania, dated Nov. 15, 1853 ; 

 from the lloyal Geographical Institute of Vienna, dated August 21, 

 1853 ; and from the Royal Academy of Sciences of Stockholm, dated 

 July 7, 1853, severally acknowledging the receipt of the Proceedings. 



From the lloyal Geological Institute of Vienna, dated August 21, 

 1853 ; from the Imperial Academy of Sciences of Vienna, dated August 

 24, 1853, and from Dr. M. Boue, addressed to Mr. Isaac Lea, severally 

 accompanying*donations to the Library announced this evening. 



Dr. S. Weir Mitchell read a paper entitled *' On the effect of some 

 states of liespiration upon the Pulse ;" which was referred to Dr. Leidy, 

 Dr. Hallowell and Dr. Piuschenber<zer. 



Mr. Lea remarked that, when recently in Paris, he had found the 

 original specimen of 3hiUeria, described by Ferussac in 1823, and again 

 described by D'Orbigny as Acostsea, which identity Mr. Lea had pointed 

 out in a paper read before the Academy in 1851, and published in Part 

 2, Vol. 2, New Series of the Journal. The specimen alluded to pos- 

 sessed the appended bivalve shell which belonged to D'Orbigny's spe- 

 cimen. 



Mr. Lea also stated that the Reptiles referred to by Dr. Mantell, as 

 occurring in the Old Red Sandstone of the North of Scotland, were now 

 believed to be of a much later date. 



Koveniher 29th. 

 Vice-President Bridges in the Chair. 



The Committee on Mr. Girard^s paper ''Researches upon Nemer- 

 teaus and Planarians '^ reported in favor of publication in the Journal. 



The Committee on the fallowing paper by Dr. Mitchell, reported in 

 favor of publication. 



On the influence of some states of Respiration upon the Pulse. 

 By S. Weir Mitchell, M. D. 



I desire to offer to the Academj'' an abstract of a paper upon the influence of 

 some states of respiration on the pulse. As the original paper will shortly ap- 

 pear at length in the American Journal of Medical Science, I shall be as brief as 

 possible. 



Laborious respiration may be studied under four heads. 



1. The movement of inspiration, thorax in motion. 



2. Complete and full inspiration, thorax at rest. 



3. The movement of expiration, thorax moving. 



4. Complete expiration, thorax at rest. 



The dynamical relations of the blood to the heart and lungs will vary in each 

 of these cases. 



During inspiratory movement the lung is expanded, and, while air passes into 

 its cells, the blood of the greater vessels and of the two hearts tends to enter its 

 sponge-like tissue, under the influence of atmospheric pressure. A reverse pro- 

 cess occurs in expiration, and some blood, as well as most of the air is driven out 

 of the lung. 



