CHAPTER XI 



HOW HARVEY DISCOVERED THAT THE HEART IS A 

 DOUBLE PUMP 



It so happened that during the two years which Harvey- 

 spent in Padua, Fabricius was making an investigation of 

 the very strange trap-doors or sluice-gates which are 

 set within veins. Some of these are depicted in fig. 27. 

 Fabricius showed his pupils that these sluice-gates or 

 valves were to be found at short intervals throughout the 

 veins of the legs, arms, and also in the veins at the root 

 of the neck. They were simple contrivances, being 

 merely a pair of minute, very delicately made watch- 

 pockets placed opposite each other within the vein. 

 There was one feature about these contrivances on which 

 Fabricius laid emphasis ; the mouths of the valve-pockets 

 were always directed towards the central part of the body 

 — towards the liver and heart. Their mouths were so 

 set as to catch the tide of blood as it flowed outwards in 

 the veins to nourish the tissues. Clearly, said Fabricius, 

 the parts which hang downwards like the legs and arms 

 would drain the blood from the central parts of the body 

 if their veins were not specially guarded. But Harvey 

 had noticed that the veins which ascend to the head also 

 had valves, and that observation set him thinking. 



Harvey was back in London in time to see the obsequies 

 which followed the death of the Great Queen and the 

 pageants which marked the arrival of the first Stuart king. 

 Presently we find him a young married man practising as 

 a physician in the city of London — his house being in 

 Knightrider Street. Now, a young doctor waiting for 



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