378 GENERAL BIOLOGY 



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

 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 Human! 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 Excercitatio Anatomica 

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

 clusively that the blood flows in a circle from the heart throughout 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 com- 

 posed. 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, \vas his 

 description of spermatozoa. His imagination ran away with him, for he 

 was sure he saw definitely-formed tiny human beings in the spermatozoa. 

 A great conflict was waged by those who agreed with him and those who 

 opposed Van Leeuwenhoek and his school (the spermists), insisting that 

 it was the sperm which was the all important factor in producing life, 



