A HISTORY OF SCIENCE 



might not be simplified. Doubtless this, like most 

 similar good sayings, is apocryphal; but whoever in 

 vented it has made the world his debtor. 



HEROPHILUS AND ERASISTRATUS 



The catholicity of Ptolemy's tastes led him, natu- 

 rally enough, to cultivate the biological no less than 

 the physical sciences. In particular his influence per- 

 mitted an epochal advance in the field of medicine. 

 Two anatomists became famous through the investiga- 

 tions they were permitted to make under the patron- 

 age of the enlightened ruler. These earliest of really 

 scientific investigators of the mechanism of the human 

 body were named Herophilus and Erasistratus. These 

 two anatomists gained their knowledge by the dissec- 

 tion of human bodies (theirs are the first records that 

 we have of such practices), and King Ptolemy himself 

 is said to have been present at some of these dissec- 

 tions. They were the first to discover that the nerve- 

 trunks have their origin in the brain and spinal cord, 

 and they are credited also with the discovery that these 

 nerve-trunks are of two different kinds one to con- 

 vey motor, and the other sensory impulses. They 

 discovered, described, and named the coverings of the 

 brain. The name of Herophilus is still applied by 

 anatomists, in honor of the discoverer, to one of the 

 sinuses or large canals that convey the venous blood 

 from the head. Herophilus also noticed and described 

 four cavities or ventricles in the brain, and reached the 

 conclusion that one of these ventricles was the seat of 

 the soul a belief shared until comparatively recent 

 times by many physiologists. He made also a careful 



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