THE SCAVENGERS OF THE BODY. 383 



to this extent simply a physical phenomenon, which MM. Mascart 

 and Bordet have clearly distinguished. As soon as a leucocyte 

 touches a resisting body it reacts to the contact by applying the 

 largest possible surface to it. It spreads out, becomes thin, 

 stretches itself along, and ceases deforming itself only after it has 

 obtained the maximum of contact. By such mechanism it pene- 

 trates objects that offer it any breach and overcomes them. "When 

 the foreign body has been disaggregated into fragments, into small 

 enough grains, phagocytosis intervenes and disposes of the remains. 

 In this way the organism sometimes rids itself of splinters of bone 

 that remain in the tissues after a fracture. So, too, the leucocytes, 

 when occasion arises, repair the blunders of surgeons by extracting 

 and absorbing forgotten objects left in wounds, while at other 

 times they act as auxiliaries by destroying things that have been 

 voluntarily abandoned in them, like threads of catgut in buried 

 sutures and drains of decalcified bone. 



There are two conditions, under normal circumstances, in which 

 phagocytosis plays a marked part. The first is the case where 

 vital action brings on the destruction of the organs or the tissues, 

 or, to use exact language, their disintegration in a solid form. 

 The wastes of organic activity are usually in liquid form, and, 

 turned into the blood, they are eliminated in that state through 

 the natural emunctories. Sometimes, however, disintegration re- 

 sults in solid wastes, and the phagocytes do the work of carrying 

 them away. This is the case with the red globules of the blood, 

 which, after a longer or shorter career, are deposited in the spleen 

 and break up into debris, some of the parts of which are insoluble 

 in the interstitial liquids. The leucocytes collect around these resi- 

 dues so thickly as sometimes to fuse themselves into a solid mass, a 

 sort of Plasmodium or giant cell which digests the debris. At other 

 times, and more rarely the isolated leucocytes are not able to absorb 

 the incorporated matters. They then conduct them to the surface 

 of the intestine and discharge them there. A like phenomenon 

 occurs in the liver. The coloring matter of the blood frequently 

 gives rise to insoluble ferruginous deposits which the leucocytes 

 have to convey to the digestive tube. This occurs when a wound 

 provokes an effusion of blood and a mortification of the red globules 

 or of the neighboring anatomical elements. All of the waste that 

 can not take the liquid form and pass in that condition into the 

 circulatory passages is incorporated within the phagocytes. The 

 mechanism of resorption of bone does not seem different. 



The phagocytes perform a similar function in another process 

 which very frequently takes place in various animals that pass 

 through metamorphoses, -as in insects whose organs are transformed 



