36 FATHERS OF BIOLOGY. 



It will be observed that here Aristotle so correctly 

 describes the position of the human heart as to render it 

 probable that he is speaking from actual inspection ; 

 although man is not the only animal in which the heart 

 is turned towards the left. In contrasting the heart with 

 the other viscera he appears to have overlooked the 

 existence of the coronary vessels, and to have imagined 

 that the nutrition of the heart was effected directly by 

 the blood in its cavities. Although the heart is not really 

 the first part to appear, the observation of its very early 

 appearance in the embiyo, which he treats more fully 

 elsewhere, 1 is alone enough to establish his reputation as 

 an original observer. It is remarkable that Aristotle 

 should have overlooked the presence of the valves of the 

 heart, the structure and functions of which were fully 

 investigated within thirty years of his death by the 

 anatomists of the Alexandrian school. This is the more 

 remarkable, as he calls attention here, and in the " History 

 of Animals," to the sinews or tendons (vevpa) with which, 

 he says, the heart is supplied, and by which he probably 

 meant chiefly the chorda tendinea. The " bone in the 

 heart " of which he speaks was probably the cruciform 

 ossification which is normally found in the ox and the 

 stag below the origin of the aorta. It is found in the 

 horse only in advanced age, or under abnormal condi- 

 tions. The statement that the heart contains no more 

 1 " History of Animals," vi. 3. 



