CHEMOTAXIS 213 



Jacob that only extracts of hematogenetic tissues showed positive 

 chemotaxis. Egg-albumen, gelatine, albumen-peptone, and 

 alkali albuminate were also positive, carbohydrates feebly so, 

 and fat not at all. Metallic copper, iron, mercury, and their 

 salts have also been found to be chemotactic substances, but it 

 is very probable that they act in part through destroying the 

 tissues in their vicinity, which give rise to decomposition-products 

 having a positive eifect. Adler, 1 however, found that bichloride 

 of mercury as dilute as 1 : 3000 caused more leucocytic invasion 

 of a piece of saturated elder pith than did even cultures of 

 pyogenic bacteria. 2 



Metchnikoif observed that leucocytes might, after a time, be 

 attracted toward substances that at first seemed to repel them. 

 If the blood is full of toxins, the subcutaneous introduction of 

 bacteria does not lead to a local accumulation of leucocytes, pre- 

 sumably because the difference in chemotaxis between the blood 

 and the tissue fluids is not great enough to cause emigration ; 

 in this connection should be mentioned Pfeffer's observation 

 that B. termo in a peptone solution will not migrate toward 

 another stronger peptone solution unless the latter is at least 

 five times as strong as the former. 



Relation of Cell Types to Migration. Of the leuco- 

 cytes, the most actively affected by chemotaxis is the polymor- 

 phonuclear variety, but not all substances affect each variety 

 of leucocyte in the same way ; for example, infections with most 

 animal parasites result in both local and general increase in the 

 eosinophilous forms, and similar effects have been obtained by 

 the injection of extracts of animal parasites. Lymphocytes are 

 much less active, presumably because they contain less of the 

 mobile cytoplasm and consist chiefly of the structurally fixed 

 nuclear substance. Undoubtedly many of the cells in so-called 

 lymphocytic accumulations seen in certain conditions, such as 

 tuberculosis, are not lymphocytes from the blood, but are newly 

 divided cells of the tissue. 3 The experimental evidence concern- 

 ing lymphocytic emigration is very contradictory. Fauconnet 4 

 has found that tuberculin injections cause in man general in- 

 crease in leucocytes, but only of the polymorphonuclear form. 

 Long-continued intoxication of animals, however, may result in 

 lymphocytic increase, but local introduction of the toxin leads to 

 accumulation of polymorphonuclear cells and not lymphocytes. 



1 Festschr. for A. Jacobi, 1900, New York. 



2 Concerning the effects of iodin and iodides upon the leucocytes, see 

 Heinz, Virchow's Arch., 1899 (155), 44. 



3 See re'sume' by Pappenheim, Folia Hematol., 1905 (2), 815. 



4 Deut. Arch. klin. Med., 1904 (82), 167. 



