70 CIRCULATION OF THE BLOOD 



craters on the surface of the moon. Galileo saw enough 

 with his telescopes to convince himself that the movement 

 of the sun round the earth was but an appearance. At 

 the very time that Harvey was giving his first course of 

 lectures securely in London, Galileo's teaching was 

 attracting the unwelcome attention of the Inquisition in 

 Rome. 



Galileo's microscopes, however, were far less satis- 

 factory than his telescopes. For optical reasons, the 

 nature of which we need not discuss, these early com- 

 pound microscopes failed to give a clear picture. With 

 any high degree of magnification the image was always 

 blurred and distorted. The seventeenth century had 

 more than passed its first half before a better device was 

 introduced. But soon after 1650 a way was found of 

 improving simple lenses of very high power. Even the 

 improved high power simple lenses only gave a clear 

 image of an exceedingly small area. Within that small 

 area, however, the image was quite clear and was not 

 much distorted. Many of the most important micro- 

 scopical discoveries of the second half of the seventeenth 

 century were therefore made with a simple lens. This 

 was notably the case with much of the work of the great 

 investigators, Marcello Malpighi, Jacob van Swammer- 

 dam, and Anthony van Leeuwenhoek, with whose work 

 on the circulation we must now briefly deal. 



Malpighi was born near Bologna in northern Italy in 

 1628, the year that Harvey's work was published. He 

 went as a student of philosophy to the University of 

 Bologna, but, having lost his parents, he changed his 

 course for that of medicine. He very soon developed 

 great ability in scientific research, and was especially 

 skilled in minute investigation. He took a medical 

 degree, and soon after, in 1656, was elected professor of 

 medicine at his own university. 



