438 PRINCIPLES OF VETERINARY SURGERY 



4. The toxin cannot be found in either the tissues or liquids of the 

 body during the entire course of the disease. 



5. During the disease it is temporarily fixed by the nerve cells and in 

 some way a new substance is produced which does not dififuse through the 

 body but remains intracellular. 



6. The nerve fibers conduct the toxin. It does not reach the nerve 

 centers through the circulation; as it does not kill by intravenous injection 

 of the toxin. — L. A. M. 



Microscopic examinations of cultures give a definite idea 

 of the variety of bacterian species found in tetanic wounds. 

 The isolation of these species is possible, but they do not 

 all act as favoring agents. This property belongs only to 

 some of them. There is 'found constantly in the wounds 

 of tetanic subjects this or that bacterium, which, combined 

 with a small dose of tetanus spores, will probably give te- 

 tanus to the cavy. Inoculated alone this bacterium does not 

 cause the disease, and acting alone the tetanus spores will 

 give negative results, but when associated tetanus is pro- 

 duced. The associated bacterium taken at the autopsy on 

 the dead tetanic subjects can be recognized as the one that 

 was introduced beneath the skin to produce the disease. 



By studying these lesions the mechanism by which the 

 micro-organisms facilitate the generation of tetanic bac- 

 illi is made apparent. In spite of their different physi- 

 ognomies these alterations are always characterized by 

 leucocytic influx ending either in a pus-like collection or 

 in the formation of a pseudo-membrane. In both cases 

 most of the leucocytes are dead, while the others are filled 

 with the micro-organisms they have englobed. The "fav- 

 oring" bacteria have the property of actively attracting 

 the leucocytes and also of killing them. The filtered cul- 

 tures act in the same manner. They seem to supply the 

 tetanus spores with the support they require by destroy- 

 ing the activity of the leucocytes, which obey their domi- 

 nant chemiotactic solicitations and then strike them dead.' 

 These experimental and significant facts interpret the 



