CHEMOTAXIS 211 



been made showing that chemical substances of many different 

 origins other than bacterial exert a chemotactic influence on 

 leucocytes. Some substances are indifferent in effect, most are 

 positive, while some are believed to repel leucocytes ; i. e. y are 

 negatively chemotactic. 



Negative Chemotaxis. Probably the substances that repel 

 leucocytes are few in number ; Kanthack, indeed, doubted the 

 existence of really negative chemotactic action upon leucocytes. 

 Verigo l also considers that as yet no actual negative chemotaxis 

 has been satisfactorily demonstrated ; but, by analogy with the 

 effects of chemicals on ameba, ciliata, and plasmodial forms, 

 which all show a decided negative chemotaxis under certain 

 influences, it would seem most probable that leucocytes also 

 should be repelled as well as attracted by chemicals. 2 



Non-bacterial Chemotactic Substances. One of 

 the earliest significant studies of the effects of non-bacterial 

 substances upon chemotaxis was made by Massart and Bordet, 3 

 who showed that products of the disintegration of leucocytes 

 and other cells had a strong positive chemotactic influence. 

 They also corroborated the statement of Vaillard and Vincent 

 that lactic acid is an actively repellant substance, for they 

 found that tubes containing a pyocyaneus culture, which ordi- 

 narily become filled with leucocytes rapidly, did not become 

 invaded at all if lactic acid was also added in a strength of 

 1 : 500, although leucocytes did enter when the dilution was 

 1 : 1000. 



Gabritchevsky 4 studied the chemical influence of a large 

 number of substances on leucocytes and divided them into 

 three groups : I. Substances exerting " negative chemotaxis/' 

 including those that attracted only a few leucocytes. 5 II. Sub- 

 stances with " indifferent chemotaxis," which attracted moderate 

 numbers of leucocytes. III. Substances with positive chemo- 

 taxis. If we correct the groupings made by Gabritchevsky 

 we have the following classification : 



1 Arch. d. Med. exper., 1901 (13), 585. 



^Salomonsen's observation (Festskrift ved indyielsen af Statens Serum 

 Institut, Kopenhagen, 1902, Art. XII), that ciliated infusoria when killed show 

 a strong negative effect on other ciliates, is of much interest, particularly as it 

 seems to be the opposite of the positively chemotactic effect of dead upon 

 living leucocytes. The negative reaction of different ciliata was specific for 

 their own kind quantitatively, but not qualitatively. 



3 Ann. d. T Inst. Pasteur, 1891 (5), 417. 



4 Ann. d. 1' Inst. Pasteur, 1890 (4), 346. 



5 Evidently these substances were not all negatively chemotactic, but were 

 relatively slightly chemotactic or indifferent ; yet in the literature generally 

 these experiments have been cited as indicating a negative chemotactic influence 

 of the substances studied. 



