THE BLOOD. 63 



plasm in which is imbedded the large, clearly discernible 

 nucleus. Their most remarkable property is that of being 

 able to throw out processes called pseudopodia and to wan- 

 der from place to place like the ordinary fresh water 

 amoeba, hence these motions are called amoeboid. By vir- 

 tue of this amoeboid movement the white corpuscles are 

 able to wander through the spaces between the tissues, and 

 even to bore their way through the delicate walls of the 

 capillaries. When such a phenomenon is viewed under a 

 microscope it is seen how a corpuscle will attach itself to 

 the side of the capillary, probably by virtue of its natural 

 stickiness. Soon there is seen projecting on the outside 

 of the capillary a tiny little process which gradually becomes 

 larger at the expense of the corpuscle until finally the full 

 corpuscle has thus wedged its way through. This phenom- 

 enon of wandering out of capillaries is especially marked 

 in the early stages of inflammation when the holes so made 

 through the capillaries frequently become so large and so 

 numerous as to permit the red corpuscles to be mechan- 

 ically forced through, and thus for the blood itself to seep 

 into the tissues, hence no doubt the redness and the swell- 

 ing of the inflammation. By virtue of this movement they 

 are further able to pick up foreign particles by flowing 

 around the particle until it is included in the cell, a method 

 exactly similar to that of the amoeba when it secures its 

 food. Foreign particles are thus literally eaten up by these 

 cells. 



As mentioned in a previous chapter, it is highly prob- 

 able that bacteria which find their way into the blood are 

 thus mechanically picked up and so rendered harmless. 

 Particles injected into the blood of transparent animals, 

 such as the water flea, being picked up by the colorless 

 corpuscles of the blood, may be watched under the micro- 

 scope. They probably serve in the disintegration of old 

 tissues, for it is possible to find in the blood of some 

 amphibians when they are losing their tails, such as the 

 change from the tadpole to the frog, some of these cells 



