THE RENAISSANCE 135 



whole circulation, and in his convincing correlation 

 of all parts of the circulatory system. He described 

 accurately everything that was visible to the naked 

 eye, so that it remained only for Malpighi, a few years 

 later, to point out, in work communicated to the 

 Royal Society of London in 1672, the capillary tubes 

 by which the blood passes from the arteries to the 

 veins, at that time first made visible by means of the 

 newly invented microscope. 



Harvey's first treatise, a small volume entitled, 

 Exercitatio Anatomica de Motu Cordis et Sanguinis, 

 was printed at Frankfort in 1628 and dedicated to 

 Charles I. His second and larger work, De Generatione 

 Animalium, was published in 1651, and contains 

 almost the first advance in embryology recorded since 

 the time of Aristotle. 



Throughout the sixteenth and seventeenth centuries, 

 new chemical substances were quickly coming to 

 The Rise of light, discovered in the search for fresh 

 Chemistry, remedies and industrial materials. But, 

 for some time, there was no corresponding advance in 

 chemical theory. Chemists continued to accept the 

 ancient view of three " elements " or " principles " in 

 the form of sulphur, mercury and salt. At last, in 1661, 

 Robert Boyle, a younger son of the great Earl of Cork, 

 in his Skeptical Chemist attacked the prevailing views 

 and revived the atomic theory, incidentally indicating 

 the true nature of heat. But for this step in advance 

 the time was not yet ripe, and the conceptions which 

 proved best suited to the needs of the age, and by which 

 the immediate advance in knowledge was won, were 

 much less in accordance with quite modern views. 



