4.8 Veterinary Medicine. 



attracts or repels the leucocytes. When it attracts the chemio- 

 taxis is said to be positive, when it repels it is negative. Among 

 negative chemiotactic agents are quinia, solutions of sodium chlo- 

 ride (io9&), and potassium salts, lactic acid, alcohol (io%), chlo- 

 roform, glycerine, jequirity, and bile. To some agents (creatine, 

 creatinine, allantoin, peptone, phlorydzine) , leucocytes are indif- 

 ferent. To gluten, wheat casein, pea legumin and the great 

 majority of pathogenic microbes, leucocytes are positively attract- 

 ed. As microbes exercise a great influence in producing local in- 

 flammation, so they are important factors in procuring an abun- 

 dant emigration of leucocytes. Some of the most fatal of micro- 

 bian diseases, like fowl cholera, repel leucocytes, and the benefit 

 of their defensive work is to a large extent lost. The toxins of 

 the chemiotactic microbe filtered from the bacteria exert the same 

 influence as the living bacteria, as shown by Gabritchevski, Mas- 

 sart and Bordet. 



But chemiotaxis may be exerted from within the bloodvessel as 

 well as from without. Bouchard, Massart and Bordet have shown 

 that a tube containing a culture of bacillus pyocyanus, introduced 

 beneath the skin of a rabbit attracts in a few hours a great num- 

 ber of leucocytes. But if, immediately after its introduction ten 

 cubic centimetres of a sterilized culture of the same bacillus are 

 injected into a vein, very few leucocytes enter the tube inserted 

 under the skin. The chemiotaxis seem to operate in this case 

 from within the blood, and the desires of the leucocytes are satis- 

 fied without leaving the vessel. It would seem that in such cases 

 the migration and protective work of the leucocytes is best ex- 

 erted at the outset of the illness and before the toxic products 

 have been poured into the blood in any quantity, whereas in the 

 advanced stages when the blood is charged with ptomaines and 

 toxins migration and phagocytosis would be likely to be limited 

 and ineffective. The same consideration would forbid the use of 

 drugs that check migration in all cases of attacks by microbes for 

 which leucocytes have a positive chemiotaxis. 



Phagocytosis is the act by which the leucocytes englobe and 

 dissolve the invading microbe. By its amoeboid movement the 

 leucocyte flows around, and envelopes the microbe for which it has 

 a positive chemiotaxis, and then begins the struggle of vitality 

 between the two living germs. If the poison (leucomaine anti- 



