THE ADRENAL SYSTEM AND PHAGOCYTOSIS. 611 



show for certain germs in preference to others. Metchnikoff's 

 doctrine as regards the power of certain leucocytes, migrating 

 and fixed, to act as phagocytes is sustained by experimental 

 evidence; the process can easily be followed visually and the 

 leucocytes be seen to ingest micro-organisms, to which they 

 are drawn by chemotactic influence. In 1862 Haeckel wit- 

 nessed the ingestion of indigo by leucocytes; in 1863 lleckling- 

 hausen observed that pus-cells were endowed with amoeboid 

 motion, and, having injected cinnabar grains in the dorsal 

 lymph-sac of frogs, saw that they were ingulfed by cells float- 

 ing in the lymph. Cohnheim in 1867 noted that the smaller 

 vessels of the mesentery became dilated and saw leucocytes 

 range themselves along the vascular walls, plunge their pseudo- 

 podia through the mural stomata, and penetrate beyond them, 

 thus migrating and becoming "pus-cells." These pus-cells, in 

 the light of MetchnikofFs theory, are the remains of protective 

 microphages which have succumbed after migrating through 

 vascular walls to meet offensively the pathogenic organism. 

 Dead material, pigment-granules, fragments of tissue, dust- 

 particles, indigo, ivory (in the osseous medullary canal, ac- 

 cording to Kolliker), in fact, almost any foreign substance 

 capable of invading the living organic structure, seems to 

 become their prey. An aseptic catgut ligature, a fragment of 

 bacilli-laden tis'sue, etc., soon becomes coated with an exudate 

 filled with leucocytes which first ingulf the bacilli and then 

 the disintegrated tissue. Let any inhibiting cause appear, 

 however, an excessively virulent germ, an abnormally high 

 temperature, for instance, their powers cease, and at once 

 the bacilli multiply, causing death of the animal used for the 

 experiment. The rapidity of the multiplication of pathogenic 

 organisms is an additional factor operating against successful 

 phagocytic action. When such is the case the phagocytes are 

 themselves destroyed. 



Successful phagocytes may be traced from their working 

 field by staining the latter, as was done by Eosenberger; long 

 lines of colored cells may then be seen to radiate in various 

 directions from the stained area. The pathogenic germs, once 

 ingulfed, usually cease to multiply, and, either through a toxic 

 action or starvation, soon die and disappear. That organisms 



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