A HISTORY OF SCIENCE 



the anatomy of men and the lower animals. It is 

 possible that he did make human dissections surrep- 

 titiously, but of this we have no proof. 



He was familiar with the complicated structure of 

 the bones of the cranium. He described the vertebrae 

 clearly, divided them into groups, and named them 

 after the manner of anatomists of to-day. He was less 

 accurate in his description of the muscles, although a 

 large number of these were described by him. Like all 

 anatomists before the time of Harvey, he had a very 

 erroneous conception of the circulation, although he 

 understood that the heart was an organ for the propul- 

 sion of blood, and he showed that the arteries of the liv- 

 ing animals did not contain air alone, as was taught by 

 many anatomists. He knew, also, that the heart was 

 made up of layers of fibres that ran in certain fixed 

 directions that is, longitudinal, transverse, and ob- 

 lique ; but he did not recognize the heart as a muscular 

 organ. In proof of this he pointed out that all muscles 

 require rest, and as the heart did not rest it could not 

 be composed of muscular tissue. 



Many of his physiological experiments were conduct- 

 ed upon scientific principles. Thus he proved that 

 certain muscles were under the control of definite sets 

 of nerves by cutting these nerves in living animals, and 

 observing that the muscles supplied by them were ren- 

 dered useless. He pointed out also that nerves have 

 no power in themselves, but merely conduct impulses 

 to and from the brain and spinal-cord. He turned this 

 peculiar knowledge to account in the case of a cele- 

 brated sophist, Pausanias, who had been under the 

 treatment of various physicians for a numbness in the 



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