1878.] 337 [Wilder. 



General Meeting. April 3, 1878. 



Vice-President Mr. S. H. Scudder in the chair. Forty-one 

 persons present. 



Mr. Scudder announced the recent sudden death of Prof. 

 C. F. Hartt, Director of the Geological Survey of Brazil, and 

 a Corresponding Member of the Society. 



Prof. B. G. Wilder, of Cornell University, exhibited to the 

 Society living examples of the western mud-fish, Amia calva. 



He showed how the breath exhaled from the very cellular and vas- 

 cular air-bladder was collected by forcing the fish to ascend into a 

 funnel connected with a glass tube supported by a frame. The air so 

 collected contained from 1 to 3.4 per cent of carbonic acid, accord- 

 ing to the time it was retained by the fish. By means of diagrams, 

 preparations, and injected specimens, Prof. Wilder also explained the 

 structure of the air-bladder, and the way in which it may receive as 

 much blood as the other viscera and the trunk. Each of the two 

 pulmonary arteries is formed by the union of the fourth opibranchial 

 artery with a branch of the third ; and each pulmonary artery is as 

 large as either the aorta or the cseliac artery. 



The fish seems to employ the aerial mode of respiration chiefly 

 when the water is stale, or muddy, or otherwise imperfectly fitted for 

 the ordinary branchial respiration. 



Further details as to the structure and habits of Amia, with refer- 

 ences to authors, are to be found in the Proc. Amer. Association for 

 Advancement of Science for 1877. 



Prof. Wilder showed an apparatus for illustrating the action of the 

 diaphragm in respiration. It consists of a tubular bell-jar with a 

 piece of elastic rubber tied across the base. The lungs of a cat are 

 suspended within the jar from a glass tube passed through a rubber 

 stopper. For use the stopper is loosened and the jar is pushed down 

 upon a convex surface (like the bottom of a flask) so as to cause the 

 rubber diaphragm to bulge upward into the jar. The stopper is then 

 made to fit lightly, and when the jar is lifted the descent of the rub- 

 ber causes the lungs to expand, the air entering through the tube. 



