138 SEVENTEENTH CENTURY. FT. in. 



(see p. 97), with lenses of such a focus as to look at an object 

 near instead of far off, anyone may easily have hit upon the 

 idea. The important point was the use made of them, and 

 this, as far as regards the structure of living beings, we 

 owe to Malpighi. 



Marcello Malpighi was born at Crevalcuore, near 

 Bologna, in the year 1628; he became Professor of Medi- 

 cine at the University of Bologna in 1656, and was early 

 distinguished for his discoveries in Anatomy, made chiefly 

 by the use of the microscope. It is not possible for us, 

 without a knowledge of anatomy, to understand thoroughly 

 the structures which he described, but we may be able to 

 form a general idea of the work he did. 



One of his first experiments was the examination of the 

 general circulation of the blood in the stomach of a frog, 

 and he succeeded in demonstrating the fact that the arteries 

 are connected with the veins by means of minute tubes 

 called capillaries, thus proving beyond doubt the truth of 

 Harvey's doctrine. His next work was to study the passage 

 of the blood through the lungs (see p. 113), and to describe 

 the air-cells from which the blood derives its oxygen. If 

 you can get anyone to show you properly under the micro- 

 scope a section of a frog's lung, you will see a number of 

 round spaces bordered by a delicate partition ; these are 

 sections of air-cells, and round them you will see a network 

 of minute tubes. Through these tubes or capillaries the 

 blood flows in a living creature, and takes up oxygen from 

 the air through the coverings or membranes of the air- 

 cells and capillaries, giving back in exchange carbonic acid 

 to be breathed out into the atmosphere. Malpighi was the 

 first to point out these air-cells and to describe the way in 

 which the blood passes over them. After this he turned his 



