236 SUSCEPTIBILITY AND IMMUNITY. 



or cold-blooded animals. This subject has Recently received much 

 attention and has been studied especially by Ali-Cohen, Massart and 

 Bordet, Gabritchevski, and others. 



According to Gabritchevski, the following substances have a neg- 

 ative chemiotaxis for the leucocytes : Sodium chloride in ten-per-cent 

 solution, alcohol in ten-per-cent solution, quinine, lactic acid, gly- 

 cerin, chloroform, bile. On the other hand, a positive chemiotaxis 

 is excited by sterilized or non-sterilized cultures of various bacteria. 

 This is shown by the fact that when a small capillary tube, closed at 

 one end, which contains the substance to be tested, is introduced be- 

 neath the skin of an animal, the leucocytes are repelled from the tube 

 by certain substances, while those which incite positive chemiotaxis 

 cause them to enter the tube in great numbers. The experiments of 

 Buchner seem to show that the positive chemiotaxis induced by 

 sterilized cultures of bacteria introduced beneath the skin of an 

 animal, is due to the proteid contents of the cells rather than to the 

 chemical products elaborated as a result of their vital activity. But 

 that such chemical products may, in some instances at least, produce 

 a positive chemiotaxis independently of the bacteria is shown by 

 the experiments of Gabritchevski with filtered cultures of Bacillus 

 pyocyanus confirmed by Massart and Bordet. 



An important observation made by Bouchard, and confirmed by 

 Massart and Bordet, is the following: When a tube containing a cul- 

 ture of Bacillus pyocyanus is introduced beneath the skin of a rabbit 

 it is found, at the end of a few hours, to contain a great number of 

 leucocytes. But if immediately after its introduction ten cubic centi- 

 metres of a sterilized culture of the same bacillus are injected into the 

 circulation through a vein, very few leucocytes enter the tube intro- 

 duced beneath the skin that is, the chemiotaxis of the leucocytes 

 for the bacilli contained in the tube has been neutralized by injecting 

 a considerable quantity of the soluble products of the same bacillus 

 into the circulation. 



Buchner, having shown that the bacterial cells contain a proteid 

 substance which attracts the leucocytes, experimented with various 

 other proteids and found that gluten, casein from wheat, and legumin 

 from peas had a similar effect. Starch has no effect, but a mass of 

 flour, made from wheat or from peas, introduced beneath the skin of 

 a rabbit or of a guinea-pig, with antiseptic precautions, in the course 

 of a day or two is enveloped and penetrated by immense numbers of 

 leucocytes. If, instead of introducing these substances which induce 

 positive chemiotaxis beneath the skin, they are injected into the cir- 

 culation, Buchner has shown that a great increase in the number of 

 leucocytes occurs. 



