PRINCIPLES OF VETERINARY SURGERY 435 



ture becomes susceptible to one-eighth to one-third of a 

 cubic centimeter of the same culture to which lactic acid 

 or trimethjlamine has been added. These chemical agents 

 have a repelling efifect on the leucocytes. At the autopsy 

 they — the leucocytes — are not found at the point of inocu- 

 lation. 



The spores may also be protected against phagocytic ac- 

 tion by chemical means, for example, by shutting them 

 up in an envelop of filter paper which is afterwards intro- 

 duced aseptically under the skin or into the peritoneum of 

 a rabbit. The paper sheath does not obstruct the passage 

 of serum to the spores to form a favorable medium for their 

 growth, l:)ut, on the other hand, on account of its thickness, 

 it retards the inward migration of the leucocytes. Under 

 this condition the spores grow, the bacilli elaborate their 

 toxins, and when the leucocytes finally reach the interior of 

 the paper, the time for effective struggle is over. The tox- 

 ins then spread through the surroundings and drive away 

 the leucocytes. 



Again, if the leucocytes are paralyzed by intravenous 

 injections of finely pulverized ^•egetable carbon, tetanus may 

 be produced by the injection of spores deprived of their 

 toxins. In this experiment, as well as in the preceding one, 

 the spores are protected against leucocytes — the latter be- 

 ing occupied with the carbon are motionless and incapable 

 of coping with the micro-organisms. 



Traumatism and foreign bodies play the same role. The 

 association of various micro-organisms with the spores of 

 the tetanus bacillus favors infection. In the natural infec- 

 tion numerous micro-organisms that live in the soil are in- 

 oculated with the specific germ, and they generate the im- 

 purities that make a favorable field for the growth of the 

 tetanus bacillus. These facts, which Verhoogen and Baer- 

 ten anticipated in 1890, were demonstrated by Vaillard Vin- 

 cent and Rouget by means of the following e.xperiments; 



