126 GLIMPSES OF NATURE. 



be taken as a fair or average estimate of their pro- 

 portion. The red corpuscles of the blood discharge 

 a very important duty in the maintenance of our lives. 

 They are the gas-carriers of the blood. They go forth 

 from the lungs laden with the oxygen we have breathed 

 in ; they return to the lungs charged with the carbonic 

 acid gas which we have to breathe out. So far, then ; 

 the use and duty of the millions of red particles in our 

 blood are not by any means matters of doubt. 



The white corpuscles, on the other hand, possess a 

 far more curious and eventful history. Each is a 

 mass or cell of living matter " protoplasm," as it is 

 named measuring in diameter the one twenty-five 

 hundredth part of an inch or thereabouts. It also 

 possesses a smaller and solid particle in its interior. 

 Now, being a mass of living matter, our white cor- 

 puscle possesses powers of independent movement ; 

 and this first fact introduces us to a startling con- 

 sideration. We possess in our blood millions of little 

 living bodies, which are, in a sense, independent of 

 us autonomous subjects, as it were, of the body at 

 large. They are not under our control in any sense ; 

 but live and move, and discharge their duties as freely 

 as if they recognised no right or title of their possessor 

 to question their acts. 



Somewhere about the year 1846, Dr. Augustus 

 Waller, observing the circulation in the finest blood- 

 vessels such as we can observe in the web of the 

 frog's foot, and in other transparent textures of that 

 convenient animal's frame declared that he saw blood 

 corpuscles, and especially white ones, insinuating their 

 way through the walls of the vessels, and, passing 

 out through these tubes, finally land amid the tissues 

 of the animal's frame. This observation, at first re- 



