THE ADVANCE OF SCIENCE 137 



He came to the conclusion that this is the chief, if not 

 the whole, value of these corpuscles in higher as well as 

 lower animals, in all of which they are very abundant. 



FIG. 40. 



FIG. 41. 



FIG. 42. 



Fig. 40. Phagocyte of a guinea-pig in the course of engulphing a very 

 mobile undulating spirillum. Fig. 41. The same, forty minutes later. 

 Fig. 42. The same taken half an hour after Fig. 41. (From Metschnikoff s 

 " Immunity.") 



It was known that when a wound bringing in foreign 

 matter is inflicted on a vertebrate animal the blood-vessels 

 became gorged in the neighbourhood and the colourless 

 corpuscles escape through the walls of the vessels in 

 crowds. Their business in so doing, Metschnikoff showed, 



FIG. 43. 



A large kind of phagocyte of the guinea-pig, 

 killed and stained for microscopic examination. 

 It shows the large spherical nucleus and three 

 specimens of the spirillum of relapsing-fever 

 which have been engulphed, and are lying 

 within its protoplasm. They would have been 

 slowly digested that is to say, dissolved by the 

 digestive juices within the phagocyte. (From 

 Metschnikoft's "Immunity.") 



is to eat up the foreign matter, and also to eat up and 

 remove the dead, wounded tissue. He therefore called 

 these white or colourless corpuscles 'phagocytes,' the 



