THE CIRCULATION OF THE BLOOD. 437 



is elaborated by the lungs, made yellow, and trans- 

 fused from the vena arteriosa into the arteria 

 venosa" This truth is, however, mixed with various 

 of the traditional fancies concerning the "vital 

 spirit, which has its origin in the left ventricle." It 

 may be doubted, also, how far Servetus formed his 

 opinion upon conjecture, and on a hypothetical 

 view of the formation of this vital spirit. And we 

 may, perhaps, more justly ascribe the real establish- 

 ment of the pulmonary circulation as an inductive 

 truth, to Realdus Columbus, a pupil and successor 

 of Vesalius at Padua, who published a work De 

 He Anatomicd in 1559, in which he claims this dis- 

 covery as his own 10 . 



Andrew Caesalpinus, who has already come under 

 our notice as one of the fathers of modern induc- 

 tive science, both by his metaphysical and his 

 physical speculations, described the pulmonary cir- 

 culation still more completely in his Qucestiones 

 Peripatetics, and even seemed to be on the eve of 

 discovering the great circulation ; for he remarked 

 the swelling of veins below ligatures, and inferred 

 from it a refluent motion of blood in these vessels 11 . 

 But another discovery of structure was needed, to 

 prepare the way for this discovery of function ; and 

 this was made by Fabricius of Acquapendente, who 

 succeeded in the grand list of great professors at 

 Padua, and taught there for fifty years 12 . Sylvius 

 had discovered the existence of the valves of the 

 10 Encyc. Brit. " Ib. ll Cuv. p. 44. 



