Physiology of Pathogenic Microbes. 67 



Bouchard has shown that gradual cooling of the 

 guinea pig allows the entry into the blood of this 

 animal of the microbes distributed on the surface of 

 the mucosa. Nervous disturbances of a depressive 

 character act in the same way: fear. 



The administration of chloral, curara, or alcohol to 

 the frog and to the dog, which are refractory to bacte- 

 ridian charbon, endows them with receptivity for this 

 disease. Antipyrine and chloral diminish the resist- 

 ance of the chicken to the same afiection. 



The attenuated and inoflFensive bacillus of symp- 

 tomatic charbon becomes pathogenic and causes the 

 disease when it is conjoined with lactic acid, or tri- 

 methylamine, or when injected into a tissue pre- 

 viously contused. The same substances, as well as a 

 similar traumatism, also favor the implantation of 

 the tetanus bacillus. 



The influence of these very diverse conditions 

 must be ascribed to the action which they exert upon 

 the phagocytes, the protective function of which they 

 diminish, by rendering them less capable of digesting 

 the microbic invaders. 



6. Influence of the quality and quantity of the virus. — 

 Receptivity naturally varies with the special degree 

 of virulence of the germs that the organism receives; 

 a germ which is toxic for a given species may become 

 an efficacious vaccine when its virulence has been en- 

 feebled. 



As to the quantity of the virulent substance, it 

 especially requires attention; the influence of the 

 dose can not be questioned ; the natural immunity of 

 Algerian sheep against charbon is overcome by inoc- 

 ulation of a large dose of the charbon bacillus. In- 



