248 INFLAMMATIOX 



causes or products of the inflammation; (2) increased osmotic pres- 

 sure in the tissues, due to increased or abnormal formation of crystal- 

 loidal substances with high osmotic pressure from large molecular 

 compounds, many of which are colloids (proteins) without apprecia- 

 ble osmotic pressure; (3) alterations in the hydration capacity of the 

 colloids, whereby, through decrease in salts or increase in acidity, 

 they come to possess a greater affinity for water (M. H. luscher). 

 By far the most characteristic feature of inflammation, however, is 

 the behavior of the leucocytes — -their increase in number in the blood, 

 their migration from the vessels and accumulation about the point 

 of injury, and their engulfing and destroying various solid particles, 

 such as bacteria and degenerating tissue elements. These processes, 

 which seem to indicate something approaching independent volition 

 on the part of the leucocytes may, however, be well explained by ap- 

 plication of known laws of chemistry and physics, without passing 

 into the realms of the metaphysical. This will be attempted under 

 the heading of: 



AMEBOID MOTION AND PHAGOCYTOSIS 



The accumulation of leucocytes at a given point in the body indi- 

 cates that some means of communication must exist between this 

 point and the leucocytes in the circulating blood. No direct com- 

 munication by the nervous system or other structural method existing, 

 the only possible explanation is that the communication is through 

 the fluids of the body, and depends upon changes in their chemical 

 composition or physical condition. As the latter generally depends 

 upon the former, the communication is considered to be accomplished 

 by chemical agencies, and called chcmotaxis. 



Chemotaxis 



Changes in the chemical composition of a fluid have been shown 

 frequently to affect the motion of living organisms suspended in it. 

 One of the earliest observations was that of Engehnann,'' who noticed 

 that Bacteriurn ternio suspended in water tended to accunuilate about 

 a l)ubble of oxj^gen in the water. Pfeffer^ discovered that the sper- 

 matozoids of certain ferns were attracted powerfully by very dilute 

 solutions of malic acid, which is contained in the female sperm cell, 

 inchcating that the migi-ation of the sperm cells in the proper direc- 

 tion depends on a chemical conuinuiication, and he projiostvl tlie t(>rni 

 ('h(uuotaxis foi" this phenomenon. Strong sohitions of malic acid, <>ii 

 the other hand, repelled spermatozoids. Cane-sugar was found to at- 

 tract the spermatozoids of a certain foliaceous moss. In the case of 

 the mali(; acid, it seems to be the anion that jircxhices the effect, since 

 salts of malic acid have exactly the same propei'ty. 



^ HotiiniHoho ZcitiiiiK, 1S81 (39), 441. 



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