518 THE ANTHRAX BACILLUS 



In cases of spontaneous infection in man and the lower animals it may be 

 stated that the less severe the local reaction the more severe the subsequent 

 septicaemia. Malignant pustule in man, where the most prominent feature 

 is the external lesion, only exceptionally leads to death [ according to 

 figures given by J. M. Legge the death rate from cutaneous anthrax is 

 nevertheless about 24 per cent, in this country (61 deaths among 255 cases 

 in six years)]. On the other hand in domestic animals the local reaction is 

 almost nil (sometimes glosso-anthrax), and death usually supervenes. 



SECTION I. THE EXPERIMENTAL DISEASE. 

 1. Susceptible and immune animals. 



1. Sheep. In sheep the disease runs a very rapid course : death often takes 

 place suddenly following an attack of hsemoglobinuria. Generally speaking 

 this species is highly susceptible to infection both by sub-cutaneous inocula- 

 tion and by ingestion ; Algerian sheep however are immune (Chauveau). 



2. Rodents. Mice, guinea-pigs and rabbits are very susceptible to sub- 

 cutaneous inoculation but are less easily infected by feeding. 



Rats generally show a higher degree of immunity. White rats are in most 

 cases immune but the immunity is not absolute and is subject to great varia- 

 tion. Young rats are more susceptible than adults of the species. 



Rats may be inoculated with anthrax bacilli several times without infecting 

 them though it is always possible that a further inoculation may produce the 

 disease (Straus). A virus virulent for adult rats can be obtained by passage 

 through young white rats (Metchnikoff). Overfeeding lowers the resistance of the 

 rat and renders it susceptible to infection (Charrin and Roger). Feser believes the 

 immunity to be more constant in animals fed on meat. 



Behring, Metchnikoff and Roux, and Sawtehenko, have shown that the serum of 

 white rats contains a lysin capable of dissolving the anthrax bacillus in vitro. 



3. Bovine animals. Cattle are very susceptible to infection through the 

 intestinal canal but are more resistant to sub-cutaneous inoculation. When 

 infected by feeding the animal is attacked with a blood-stained diarrhoea, 

 colic, sweating and convulsions and dies after a few hours' illness. 



4. Horses. The horse is not often infected through the intestinal canal, 

 though intestinal anthrax occurs as an epizootic among horses in Russia and 

 in Corsica. [The epizootics of anthrax in Siberia are known as Siberian 

 fever.] Horses are more susceptible than cattle to sub-cutaneous inocula- 

 tion. 



5. Pigs. These animals are almost entirely immune to anthrax. 



Carini has recorded the occurrence in Brazil of an anthrax infection of pigs accom- 

 panied by swelling of the cervical glands (qarotilho), but has been unsuccessful in his 

 attempts to reproduce the disease experimentally. 



6. Carnivora. As a rule these animals are only slightly susceptible to 

 anthrax. Bears and cats seem more susceptible than other animals of this 

 family. The fox is immune (Amler). 



Dogs are naturally immune to anthrax [but spontaneous infection has been 

 observed following upon the consumption of infected horse meat]. Sub-cutaneous 

 inoculation generally results in the formation of an abscess in which active 

 phagocytosis takes place so that the animal escapes a generalized infection. The 

 immunity of the dog may be overcome by inoculating very large quantities of the 

 virus into the veins, by the intra-venous inoculation of an emulsion of wood- 

 charcoal, by extirpation of the spleen, etc. Young dogs readily succumb to 

 intra-pleural inoculation (Nocard). A mad dog inoculated with 1 c.c. of a culture 

 harmless to a healthy dog dies of anthrax in less than 24 hours. The virus thus 



