382 POPULAR SCIENCE MONTHLY. 



getic and most special agencies of living chemistry, to the ferments 

 which determine the coagulation of the blood when drawn from 

 the vessels (coagulating ferment, or thrombosis) and the consump- 

 tion of sugar (glycolytic ferment), and to numerous diastases. The 

 presence of nuclein in their bodies involves consequences which 

 we are only beginning to perceive. 



Behaving like independent beings, the leucocytes or phagocytes 

 perform similar functions with those of the highest animals, feed- 

 ing, respiring, and reproducing themselves; they move and feel — 

 that is, are impressed by internal excitants. These operations, how- 

 ever, assume with them a character of extreme simplicity. They 

 seem to be the direct result of the physical and chemical proper- 

 ties of the protoplasm that composes them, so that the mysterious 

 side of those vital functions nearly vanishes when we scan them in 

 these their very beginnings. Their respiration is the effect of a sort 

 of affinity between their substance and the vital gas — a ehimiotac- 

 tism directing them toward oxygen. This may be illustrated by 

 forming a microscopic preparation of fresh lymph, imprisoning a 

 few bubbles of air, and sealing it hermetically with paraffin. 

 After two or three hours we can see the leucocytes grouped around 

 the bubbles. When the provision of air is exhausted, several hours 

 afterward, the leucocytes will cease to move and become inert. 

 On inserting a needle, the contact of the air revives them. 



The faculty possessed by the leucocytes of- seizing solid cor- 

 puscles coming in contact with them, inglobing them, and absorb- 

 ing them, or, as M. ]\Ietchnikoff calls it, intracellular digestion or 

 phagocytosis, is easily observed. If we mix fine granulations of 

 carmine or cinnabar, mingled with slightly salted water, with a 

 drop of lymph, we can see the coloring matter penetrating the leu- 

 cocytary protoplasmic mass, which is soon stuffed with it. The 

 anatomo-pathologists had already observed, in tattooed subjects, 

 white globules charged with grains of charcoal or vermilion. It 

 is legitimate to conclude that some parts of the coloring matter 

 that had been introduced under the epidermis had been taken up 

 by the white globules. This proceeding has been observed in the 

 very act by M. Metchnikoff. 



A classic experiment illustrating this operation is now common 

 in our laboratories, and the fact of phagocytosis has come to be 

 regarded as incontestable. 



The generality of the phenomenon results from the leucocyte 

 preserving its phagocytic faculty in all its peregrinations, and these 

 peregrinations are unlimited. The tendency of the nomadic ele- 

 ments to push on and insinuate themselves into the finest inter- 

 stices and the narrowest passages is a rudiment of a tactile sense, 



