CHANNELS OP INFECTION. 



Infection through the mucous membrane of the intestine no 

 doubt occurs in certain diseases. This is believed to be a common 

 mode of the infection of sheep and cattle with anthrax, and probably 

 also in the infectious disease of swine known as hog cholera. The 

 anthrax bacillus would be destroyed by the acid secretions of the 

 stomach, but if spores are present in food ingested they will reach 

 the intestine. The experiments of Korkunoff do not, however, sup- 

 port the view that infection is likely to occur in this way. In a series 

 of experiments upon white mice fed with bread containing a quantity 

 of anthrax spores the result was uniformly negative, but exception- 

 ally infection occurred in rabbits. The same author obtained posi- 

 tive results in rabbits fed with food to which a pure culture of the 

 bacillus of chicken cholera had been added. 



Buchner, in experiments upon mice and guinea-pigs fed with 

 material containing anthrax spores, obtained a positive result in four 

 out of thirty-three animals. This is no doubt the usual mode of in- 

 fection in typhoid fever in man. 



Infection may also occur through the mucous membrane of the 

 respiratory organs. This has been demonstrated by several bac- 

 teriologists, and especially by the experiments of Buchner, who 

 mixed dried anthrax spores with ly cop odium powder or pulverized 

 charcoal, and caused mice and guinea-pigs to respire an atmosphere 

 containing this powder in suspension. In a series of sixty- six experi- 

 ments fifty animals died of anthrax, nine of pneumonia, and seven 

 survived. That infection did not occur through the mucous mem- 

 brane of the alimentary canal was proved by comparative experi- 

 ments in which animals were fed with double the quantity of spores 

 used in the inhalation experiments. Out of thirty-three animals fed 

 in this way but four contracted anthrax. That infection occurred 

 through the lungs was also demonstrated by the microscopical ex- 

 amination of sections and by culture experiments, which showed that 

 the lungs were extensively invaded, while in many cases the spleen 

 contained no bacilli. Positive results were also obtained with cul- 

 tures of the anthrax bacillus not containing spores, which the ani- 

 mals were made to inhale in the form of spray. But in this case a 

 considerable quantity was required, and a sero-fibrinous pneumonia 

 was usually produced as well as general infection; the inhalation of 

 > mall quantities gave no result. Positive results in rabbits were also 

 >l>taim>d by causing them to inhale considerable quantities of a spray 

 containing the bacillus of chicken cholera. 



The fact that large quantities of a liquid culture of these virulent 

 bacilli were required to infect very susceptible animals by way of 

 the pulmonary mucous membrane, and that Buchner failed to cause 

 tht infection of tluse animals with small quantities of a pure culture 



