EXPERIMENTAL INOCULATION 537 







1. By inoculation of specifically infected pus from a wound in man or the 

 lower animals. 



2. By inoculation of soil. 



3. By inoculation of a pure culture of the bacillus. 



4. By inoculation of the spores from a culture of the organism. 



5. By inoculation of tetanus toxin (vide infra). 



Whatever the mode of infection the tetanus bacillus never invades the 

 tissues of the organism but remains strictly localized at the site of inoculation. 



When animals have been inoculated intra-venously or into the peritoneum with 

 a large dose of culture the bacillus may be found in cultures sown with the blood 

 and internal organs. Sanchez Toledo and Veillon occasionally obtained a growth 

 of the bacillus from the blood of an animal dead of tetanus by allowing a certain 

 time to elapse after death before sowing the cultures. But these results are quite 

 exceptional. 



A few hours after inoculation the bacilli have diminished in number and 

 it is not long before their presence at the site of injection can only be demon- 

 strated by culture methods. If a minimal lethal dose be inoculated, the 

 material collected post mortem from the infected part is not infectious on 

 reinoculation. On the other hand, pus from an infected wound will convey 

 the disease to susceptible animals but it is impossible to effect more than 

 four passages from animal to animal. The second passage animal does not 

 die so quickly as the first and so on ; at the fourth passage the virulence of 

 the bacillus is greatly diminished. 



1. Inoculation of soil or infected pus. 



The inoculation is best effected either beneath the skin or into the muscles 

 of the thigh of a guinea-pig or mouse. 



Symptoms and lesions. A swelling forms at the site of inoculation and 

 the part is puffy and painful ; 3 or 4 days after the inoculation symptoms 

 of tetanus appear beginning in the neighbourhood of the infected area, and 

 becoming generalized : the slightest stimulus, such as a noise, a draught of 

 air, a touch etc., will produce spasmodic movements. The clinical condition 

 is exactly the same as in human tetanus. Death occurs 2448 hours after 

 the onset of the symptoms. 



Post mortem : at the site of inoculation there will either be a purulent focus, 

 or a lesion resembling a dry yellow slough, or a thick membranous exudate. 

 The neighbouring tissues are the site of an oedematous infiltration. On 

 microscopical examination numerous other micro-organisms one or two 

 species predominating will be found associated with the tetanus bacillus. 

 The purulent, membranous and necrotic lesions are due to organisms other 

 than the tetanus bacillus. The internal organs are healthy and merely show 

 a slight congestion due to the embarrassed respiration which precedes death. 



2. Inoculation of pure cultures. 



Infection may be set up by inoculating pure cultures sub-cutaneously, 

 intra-muscularly, intra-peritoneally, intra-venously, sub-durally or on to the 

 ocular conjunctiva. Ingestion is the only mode of introduction which fails 

 to produce the disease. Sub-cutaneous or intra-muscular inoculation is the 

 most certain and rapid method of infecting an animal. 



Very small doses of broth cultures suffice to set up the disease in susceptible 

 animals. 0'02 c.c. will produce a typical tetanus in mice and guinea-pigs : 

 the symptoms begin 12-20 hours after inoculation and terminate fatally in 

 36-40 hours. 



In the case of rabbits, a dose of 0'5-1'5 c.c. is necessary and even then the 



