The History of Biology 379 



period from about 1250 to 1500 is, therefore, called the Renaissance or 

 period of re-birth. 



During the thirteenth century, the Dominican Monk, Albertus 

 Magnus (1193-1280), began working on physical experiments, while the 

 Dominican, Thomas Aquinas (1225-1274), began to collect and coordi- 

 nate all the scientific and philosophical knowledge of his day. 



Following these came the Franciscan Monk, Roger Bacon (1214- 

 1294), the real father of modern science. Among his many writings 

 we find the first clear and unmistakable statements from which our 

 knowledge of modern lenses date. His work is like a modern mono- 

 graph in that it gives recognition to the opinions of others. 



The old Romans had, it is true, used pieces of glass with water in 

 between for magnifying purposes, but it was Bacon who set men on 

 the right path regarding true observation, description, and the use of 

 modern laboratory instruments. 



Gesner (1516-1565) wrote his Historia Animalium in several vol- 

 umes between 1551 and 1587, which was widely read, although he had 

 but little influence on successive generations. 



The next truly great name in the history of Biology is that of 

 Vesalius (1514-1564). He wrote the De Humani Corporis Fabrica in 

 1543. Up to this time the surgeon would not soil his hands by touching 

 and cutting the body. Such work was left for barbers, who performed 

 their dissections and operations under the direction of the surgeon. 

 Vesalius dissected with his own hands, and then described and pictured 

 what he found. Vesalius' old master, Jacobus Sylvius, was a strenuous 

 opponent of his pupil, as was also Vesalius' own pupil, Columbus. How- 

 ever, another pupil of Vesalius, who later became his successor at the 

 University of Padua, was Fallopius (1523-1562), who built upon the 

 work of his master. 



Harvey (1578-1657) in 1628 published his Exceircitatio Anatomica 

 de Motu Cordis et Sanguinis in Animalibus, in which he showed con- 

 clusively that the blood flows in a circle from the heart through the 

 blood-vessels and back again to the heart. 



In about 1600, compound microscopes were invented, and it is from 

 this time forward that the great microscopical discoveries were made, 

 which have changed our modern conception of many ancient problems. 



Robert Hooke (1635-1703) wrote his Micrographia in 1665, in which 

 he called attention to the "little boxes or cells" of which plants are 

 composed. It is he, therefore, who gave us our first notion of the cell. 



The next important name is that of Van Leeuwenhoek (1632-1723) 

 who first saw bacteria, infusoria, yeast, rotifers, hydra, and a host of 

 other organisms which were totally unknown up to his time. His work, 

 which attracted most attention in the scientific world, however, was his 

 description of spermatozoa. His imagination carried him away, for he 



