76 THE PHILOSOPHY 



into the pulmonary artery, and, after circulating through the 

 lungs, returning into the left auricle by the pulmonary vein, 

 palTes diredlly from the right to the left auricle through an 

 aperture called the foramen ovalc^ v/hich is fituated in the 

 partition of the heart that feparates the cavities of the two 

 auricles. By this contrivance, the mafs of blood, without 

 deviating into the lungs, enters the aorta, and is diftributed 

 over every part of the body. In man, and the other terref- 

 trial animals, the foramen ovale of the heart, which permits 

 the fcetus to live without refpiration, clofes the moment af- 

 ter birth, and remains fhut during life. Animals of this con- 

 ftru(5tion can neither live v/ithout air, nor remain long under 

 water without being fuffocated. 



But, in the feal, walrus, and other amphibious animals, 

 the foramen ovale continues open during life, though the 

 mothers bring forth on land, and relpiration commences 

 immediately after birth. By means of this perpetual aper- 

 ture in the feptum or partition of the heart, which allows a 

 direct communication of the blood from the vena cava to the 

 aortajthefe animals enjoy the privilege of refpiring, or not,at 

 their pleafure. 



This fingularity in the flru^lure of the heart, and the 

 confequent capacity of living equally on land and in water, 

 mufl necelTarily produce fom.e peculiarities in the manners 

 and difpolitions of amphibious animals. The feal, accord- 

 ingly, whofe hiftory is beft known, may be confidered as 

 holding the empire of the filent ocean. To this dignity he 

 is entitled by his voice, his figure, and his intelligence, which 

 render him fo fuperior tothe fiflies, that they feem to belong 

 to another order of beings. Though his oeconomy be very 

 different from that of our domeftic animals, he is fufcepti- 

 ble of a fpecies of education. He is reared by putting him 

 frequently in v/ater. He is taught to give a lalute with his 

 head and his voice. He approaches when called upon. His 



