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COLLOIDS IN BIOLOGY AND MEDICINE 



L. HIRSCHFELD is supported in his theory by the statement of H. 

 BECHHOLD* that lactic acid (H ions) increase the phagocytic activ- 

 ity of leucocytes, whereas alkalis (OH ions) are without such effect. 



This introduces us to one of the most important fields as yet [al- 

 most] untouched by colloid investigation, chemotaxis, the experimental 

 study of which from modern viewpoints ought to prove most promising. 



In 1884, E. STAHL and DE BARY on the one hand, and W. PFEFFER 

 on the other, simultaneously gave their attention to the nature of 

 chemotaxis. They studied the lower monera, plasmodia of myxo- 

 mycetes (slime fungi) bacteria, flagellates, wheel animalcules, the 

 clustered spores of algae, the spores of ferns, mosses, etc. The essence 

 of chemotaxis lies in the attraction of these unicellular organisms 

 by certain substances (positive chemotaxis) and their repulsion by 

 others (negative chemotaxis) } while other substances do not affect 

 them at all. If for instance a cane sugar solution is placed in a 

 very narrow test tube, and the open end is dipped into a drop of 

 moss spores, the latter will pass into the tube, attracted by the 

 cane sugar. It is necessary to assume some such chemotactic re- 

 lation between eggs and spermatozoa, especially of aquatic animals, 

 as the spermatazoa discharged into the water are attracted by the 

 eggs. We owe our knowledge of the chemotactic action of leuco- 

 cytes of the higher animals to C. A. PEKELHARING and especially to 

 TH. LEBER who gives in his classical work, "Die Entstehung der 

 Entziindung," a wealth of experiments in which the most varied 

 substances were introduced into the eyes of rabbits. In the same 

 field, but it is quite obvious independently, he was followed by MAS- 

 SART and J. BORDET. 



We reproduce the following series of substances with a chemotactic 

 action (after A. GABRITSCHEWSKY) to show how difficult it is to ex- 

 plain the existence of chemotaxis on a single principle. 



SUBSTANCES SHOWING CHEMOTAXIS. 



