248 SUSCEPTIBILITY AND IMMUNITY. 
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 
pyocyaneus—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 pyocyaneus is introduced beneath the skin of a rabbit 
it is found, at the end of afew hours, to contain a great number of 
leucocytes. Butif 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. 
