EXPERIMENTAL INFECTION 519 



obtained is considerably increased in virulence and can be used for passage 

 experiments in dogs (Martel). 



7. Birds. Fowls are naturally immune to anthrax. The insusceptibility 

 of this species has however been overcome experimentally in several ways. 

 Pasteur, for instance, succeeded in rendering fowls susceptible by keeping 

 their legs in cold water at a temperature of 25 C. : Wagner obtained the 

 same result by lowering the temperature by means of repeated inoculations 

 of antipyrin : Canalis and Morpugo by experimenting while the animals 

 were fasting, etc. 



The pigeon is less highly immune than the fowl and readily succumbs 

 to the inoculation of anthrax bacilli into the anterior chamber of the eye. 

 Young pigeons are much more susceptible than adults. 



A virus which has been passed through dogs readily kills pigeons (Martel). The 

 virulence of the bacillus is also increased by passage through pigeons and after 

 several such passages a virus is obtained which on sub-cutaneous or intra- muscular 

 inoculation will kill a full-grown pigeon and even a fowl (MetchnikofF). 



8. Cold-blooded vertebrata. Batrachians are immune to anthrax. Gibier 

 has, however, been able to infect frogs by keeping the inoculated animals 

 in water at 35 C. Catterina succeeded in infecting newts. 



Sabrazes and Colombot have shown that hippocampi (Lophobranchiata) are 

 susceptible to anthrax. These animals kept under the normal conditions of their 

 existence die a few days after the sub-cutaneous inoculation of 0*25 c.c. of a broth 

 culture. Sabrazes and Colombot attribute this susceptibility to the absence of a 

 spleen and the small number of leucocytes in the blood of hippocampi. 



9. Invertebrata. Slugs are naturally immune to anthrax (Kowalewsky), 

 but Lode has succeeded in infecting them by keeping them at a temperature 

 of 32 C. and inoculating them in the body cavity. 



2. Methods of inoculation. 



1. Sub-cutaneous inoculation. Inject sub-cutaneously with the ordinary 

 precautions a few drops of anthrax blood, or, better a few drops of a young 

 broth culture of anthrax bacilli. 



Broth cultures incubated at 37 C. for 2 or 3 days are more virulent than the 

 blood with which they were sown, probably on account of the presence of antibodies 

 in the anthrax-infected blood. 



2. Ingestion. -Pasteur and Chamberland infected sheep with anthrax by 

 mixing thorns and splinters of wood previously watered with spore-bearing 

 cultures of anthrax with their food. 



3. Intra- venous inoculation. Inject a small quantity 'of a broth culture 

 into a vein. Anthrax blood should never be used for intra-venous inoculation 

 for fear of producing a fatal embolism. 



4. Intra-muscular inoculation. This method is sometimes used in the case 

 of birds, the ordinary technique being adopted. 



3. Symptoms and lesions in experimental animals. 



The symptoms and lesions in the guinea-pig and rabbit after sub-cutaneous 

 inoculation will be described, as these are the animals most commonly used 

 for experimental purposes, and this the usual form of infection. 



A. Symptoms. Local reaction. Eight to fifteen hours after inoculation 

 a small oedematous puffiness appears around the site of inoculation. The 

 neighbouring glands then become swollen and the temperature rises 1 or 

 2C. 



General reaction. For the first 24 or 30 hours in the case of the guinea- 

 pig and for 30-50 hours in the case of the rabbit the animal shows no symptoms, 



