14 Vesalius: [lect. 



" uses it for the cooling of the innate heat, for the nourishment 

 "of its substance and for the preparation of the vital spirits, 

 " elaborating and refining this air so that it together with the 

 "blood which soaks plentifully through the septum from the 

 "right ventricle into the left may be assigned to the great 

 " artery, (the aorta) and so to the whole body." 



And again, 



" The septum of the ventricles, composed as I have said 

 " of the thickest substance of the heart, abounds on both sides 

 " with little pits impressed in it. Of these pits, none, so far at 

 " least as can be perceived by the senses, penetrate through 

 " from the right into the left ventricle, so that we are driven to 

 " wonder at the handiwork of the Almighty, by means of which 

 " the blood sweats from the right into the left ventricle through 

 " passages which escape human vision." 



Even in this which he ventured to print the sarcastic note 

 of scepticism makes itself heard ; but what he really thought 

 he did not dare to put forward. He tells us in a later writing 

 that " he accommodated his statements to the dogmas of Galen " 

 not because he thought that " these were in all cases consonant 

 " with truth but because in such a new great work he hesitated 

 " to lay down his own opinions, and did not dare to swerve a 

 " nail's breadth from the doctrines of the Prince of Medicine." 



That physiological problems were before his mind, that he 

 had thought over, and indeed had tried to solve them by 

 experimental methods, is shewn in the brief chapter, ' Some 

 Remarks on the Vivisection of Animals,' which is the last 

 chapter in his great work. In this he relates his experiments 

 on muscle and nerve, shewing that that which passes along a 

 nerve in order to bring about movement passes by the substance 

 and not by the sheath of the nerves. He tells us that it is 

 through the spinal cord that the brain acts on the trunk and 

 limbs, that an animal can live after its spleen has been 

 removed, that the lungs shrink when the chest is punctured, 

 that the voice is lost when the recurrent laryngeal nerve is cut, 

 that by artificial respiration an animal can be kept alive though 

 its chest is laid wholly bare, and that under these circumstances 



