OP NORTH AMERICA. 2537 



you an opportunity of adding them to your paper, which I 

 understand will soon l^e published. This dissection was 

 performed on the 0th of January, 1834. 



f . I forced air into the vena cava ascendens, which inject- 

 ed the right auricle and ventricle, passed into the lyngs 

 through the pulmonary artery, and into the splanchnic aorta, 

 also into the systemic aorta through the valvular opening at 

 the base of the former. 



S. I forced air into one of the pulmonary veins, which in- 

 flated the left auricle and ventricle, passed into the systemic 

 aorta and the subclavian trunks which leave the supercordal 

 sack. 



The apex cordis was not attached to the pericardium, as is 

 usually the case. 



Tiie circulation of these animals is briefly as follows ; 



The blood passes from the right auricle into the ventricle 

 of the same side. From this cavity there are three open- 

 ings: — 1. One into the systemic aorta, by a valvular com- 

 munication at its base, which allows the continuation of the 

 circulation, when the progress of the blood through the lungs 

 is impeded by expiration. — 2. One into the pulmonary ar- 

 tery — 3. And one into the splanchnic aorta, carrying black 

 blood to the viscera. During expiration, there is still some 

 pulmonic circulation; a small quantity of blood passing froni 

 the lungs into the left auricle to the ventricle of the sanie 

 side, from whence it has a direct passage into the systemic 

 aorta. The valve at its base will not permit even wind to 

 pass into the right side ; nor will the semilunar valves of the 

 aorta permit regurgitation ; so that the only mixture of the 

 black and red blood takes |)lace in the systemic aorta, dur- 

 ing expiration or collapse of the lungs. 



With sentiments of respect, 



I remain your friend, ^'c. 



R. HARLAN. 

 N. M. Hentz, Esq. 



