62 BIOLOGY AND ITS MAKERS 



conditions he was not destined to live many years. He died 

 there, in. 1694, of apoplexy. His wife, of whom it appears 

 that he was very fond, had died a short time previously. 

 Among his posthumous works is a sort of personal psychology 

 written down to the year 1691, in which he shows the growth 

 of his mind, and the way in which he came to take up the 

 different subjects of investigation. 



In reference to his discoveries and the position he occupies 

 in the history of natural science, it should be observed that 

 he was an " original as well as a very profound observer." 

 While the ideas of anatomy were still vague, " he applied him- 

 self with ardor and sagacity to the study of the fine structure 

 of the different parts of the body," and he extended his inves- 

 itgations to the structure of plants and of different animals, 

 and also to their development. Entering, as he did, a new 

 and unexplored territory, naturally he made many discover- 

 ies, but no man of mean talents could have done his work. 



Activity in Research. During forty years of his life he 

 was always busy with research. Many of his discoveries had 

 practical bearing on the advance of anatomy and physiology 

 as related to medicine. In 1661 he demonstrated the struc- 

 ture of the lungs. Previously these organs had been regarded 

 as a sort of homogeneous parenchyma. He showed the pres- 

 ence of air-cells, and had a tolerably correct idea of how the 

 air and the blood are brought together in the lungs, the two 

 never actually in contact, but always separated by a mem- 

 brane. These discoveries were first made on the frog, and 

 applied by analogy to the interpretation of the lungs of the 

 human body. He was a comparative anatomist, and the 

 first to insist on analogies of structure between organs 

 throughout the animal kingdom, and to make extensive 

 practical use of the idea that discoveries on simpler animals 

 can be utilized in interpreting the similar structures in the 

 higher ones. 



