172 CLINICAL BACTERIOLOGY. 



with streptococci is responsible for the development of the 

 dangerous condition known as streptococcous typhoid septi- 

 cemia. The investigations of Vincent have shown that the 

 presence of the streptococcus and artificial mixed cultures 

 materially increases the virulence of typhoid-bacilli. The 

 staphylococcus pyogenes, the diplococcus lanceolatus 

 Frankel, and the proteus, likewise frequently find oppor- 

 tunity to gain lodgment in the organism enfeebled by 

 typhoid fever, and to give rise to the development of fur- 

 uncles, cutaneous abscesses, bronchopneumonia, catarrh of 

 the middle ear, gangrene of the skin, and the like. 



Experiments on Animals, Mice, guinea-pigs, rabbits, 

 goats, etc., die after the introduction of virulent Eberth- 

 Gaffky bacilli, with decline of temperature, convulsions, and 

 diarrhea. Considerable numbers of bacteria are necessary 

 in subcutaneous introduction, while smaller numbers suffice 

 in intraperitoneal and intravenous inoculation. The fatal 

 result is brought about under these conditions through 

 intoxication. If the virulence of the infectious agents is 

 marked, the animals, and especially white mice, may, how- 

 ever, be destroyed by intraperitoneal injection of quite 

 small numbers of bacteria, although large numbers of the 

 bacilli are found in the blood after death. It is certain 

 that under these conditions an increase has taken place in 

 the number of bacteria, and it can, therefore, not be denied 

 that the disease induced in animals by typhoid-bacilli dis- 

 plays the characters of a true infection. 



The development of actual typhoid fever in animals (and 

 also mere typhoid-bacilli intoxication) in consequence of 

 introduction of the bacteria through the mouth is attended 

 with serious difficulties. It is, however, to be observed 

 that a true typhoid disease appears not to exist naturally in 

 animals. If preliminary treatment is employed similar to 

 that adopted in the experimental development of cholera 

 alkalinization of the gastric contents, and injection of tinc- 

 ture of opium changes are at times induced in guinea-pigs 

 by the introduction of typhoid-bacilli through the mouth that 

 in some degree are suggestive of those of typhoid fever in 

 human beings. Experiments on animals of a completely 

 positive character, with the pathologic-anatomic lesions of 

 true typhoid fever, have not been recorded in the literature. 



The pyogenic activity of the typhoid-bacillus can be 

 readily demonstrated in experiments on animals. 



