yON-BACTERIAL CHEMOTACTIC SUBSTANCES 259 



nets having a positive effect. Adler,^* however, found that bichloride 

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

 piece of saturated older pith than did even cultures of pyogenic bac- 

 teria.^" 



^Tetehnikoft' obsemcd tliat leucocytes might, after a time, be at- 

 tracted 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, presumably because the 

 difference in chemotaxis between the blood and the tissue fluids is not 

 great enough to cause emigration ; in this connection should be men- 

 tioned Pfeffer's observation that B. termo in a peptone solution will 

 not migrate toward another stronger peptone solution, unless the lat- 

 ter is at least five times as strong as the former. Leucocytes will mi- 

 grate freely toward substances that kill them; of the bacterial prod- 

 ucts the toxins of pyocyaneus and diphtheria bacilli being especially 

 destructive and causing typical karyorrhexjs.-° Substances soluble 

 in lipoids are said by Hamburger ^^ to increase phagocytic activity 

 when in extreme dilutions, although stronger concentrations are highly 

 toxic for leucocytes. If an electric current is passed through two fin- 

 gers there will be found more leucocytes in the tissues of the cathode' 

 finger than in the anode finger, presumably because the OH-ions in- 

 crease ameboid movement. "^^ 



]\rany substances have been used to increase the number of leuco- 

 cytes in the circulating blood in the hope of increasing resistance to 

 infections, a result that does not seem to follow artificial leucocytosis 

 with any recognizable uniformity. A compilation of the literature 

 on this subject by Gehrig -'^'^ shows such contradictor}' findings as to 

 indicate that most of the recorded M'ork is of little value. He was 

 unable to corroborate the current statement that antipyretic drugs 

 increase the number of leucocytes in the blood. Nucleinic acid and 

 tissue extracts seem to increase circulating leucocytes with considerable 

 regularity, while witli thorium-A' and benzol they can be reduced to 

 almost complete extinction. The behavior of inflammatory processes 

 in animals thus deprived of available leucocytes has considerable ex- 

 perimental interest.-^'^ If less than 1000 leucocytes per cubic mm. 

 are present in the blood, no leucocytic exudate can be produced, ^^"* 

 although the other features of inflammation occur as usual. 



Relation of Cell Types to Migration. — Of the leucocytes, the 

 most actively affected by chemotaxis is the polymorphonuclear vari- 



is Festschr. for A. Jacobi, 1000, Xew York. 



10 Concernincr th^ effects of iodin and iodides Tij>on tlio leueocvtes, see Heinz, 

 Virohow's Arch., 1809 (1.55). 44. 



20 Schiirmaiin, Cent. f. Pathol.. 1010 (21). .3.37. 



21 Arch. N^erland.. 1912 (III, B), 1.34: Brit. Med. .Jour., 1016 (1), 37. 

 2iaSchwvzer, Bio<'heni. Zeit.. 1914 (60), 454. 



2ibZeit. exp. Path.. 1015 (17), 161. 



2ieSee G. Rosenow, Zeit. exp. Med.. 1914 (3). 42. 



2i<i Camp and Baumgartner, Jour. Exp. Med., 1915 (22), 174. 



