The Cardinal Conditions of Infection 85 



guinea-pigs kept in cages some of which were placed over the open- 

 ing of a privy, while in others the excreta of the animals were 

 allowed to accumulate, suffered from a pronounced diminution of 

 the resisting powers. This would seem to be inconsistent with the 

 habits of rats, many of which live in sewers. Abbott* caused rabbits 

 to breathe air forced through sewage and putrid meat infusions 

 for one hundred and twenty-nine days, and found that the products 

 of decomposition inhaled by the animals played no part in producing 

 disease, or in inducing susceptibility to it. 



Fatigue is a well-recognized clinical cause of susceptibility to 

 disease, and experimental evidence of its correctness is not wanting. 

 Charrin and Rogerf found that white rats, which naturally resist 

 infection with anthrax, succumbed to the infection if compelled to 

 turn a revolving wheel until exhausted before inoculation. 



Exposure to cold seriously diminishes the resisting power of the 

 warm-blooded animals. It is an everyday experience that chilling 

 the body predisposes to "cold" and may be the starting-point of 

 pneumonia. • Pasteur found that fowls, which resist anthrax under 

 normal conditions, succumbed to infection if kept, for some time, in 

 a cold bath before inoculation. 



The reverse seems to be true of the cold-blooded animals, for 

 GibierJ found that frogs, naturally resistant to the anthrax bacillus, 

 would succumb to infection if kept at 37°C. after inoculation. 



Diet produces some variation in the resisting powers. The 

 tendency of scorbutics to suffer from infectious disorders of the mouth, 

 the frequency with which epidemics of infectious disease follow 

 famines, and the enterocolitis of marasmatic infants, illustrate the 

 effects of insufficient food in predisposing to disease. We also find 

 that the infectious diseases of carnivorous animals are not the same 

 as those of herbivorous animals, and that the former are exempt 

 from many disorders to which the latter quickly succumb. Hankin 

 was able to show experimentally that meat-fed rats resisted anthrax 

 infection far better than rats fed upon bread. 



Intoxication of all kinds predisposes to infection. Platania§ 

 found that such animals as frogs, pigeons, and dogs became sus- 

 ceptible to anthrax when under the influence of curare, chloral, 

 and alcohol. Leo|| found that white rats fed upon phloridzin became 

 susceptible to anthrax. Wagner** found that pigeons become sus- 

 ceptible to anthrax when under the influence of chloral. Abbottft 

 found the resisting powers of rabbits against Streptococcus pyogenes 

 and Bacillus coli diminished by daily intoxication with 5 to 15 c.c. 



* "Trans. Assoc. Amer. Phys.," 1895. 

 t " Compte rendu Soc. de Biol de Paris," Jan. 24, 1890. 

 t "Compte rendu Acad, des Sciences de Paris," 1882, t. xcix, p. 1605. 

 §See -Sternberg's "Immunity and Serum Therapy," p. 10; "Centralbl. f. 

 Bakt," etc., Bd. vii, p. 405. 



II "Zeitschrift fiir Hyg.," 1889, Bd. vii, p. 505. 



** "Wratsch," 1890, 39, 40. 



ft "Jour, of Exp. Med.," 1896, vol. i. No. 3. 



