72 Manual of Veterinary Microbiology. 



The doctrine of the impregnation of the humors is 

 happily supplemented by that of the modification 

 of the solid parts of the organism, the anatomical 

 elements. 



In acquired immunity, whether it be consecutive to 

 a first attack of the disease or be conferred by vac- 

 cination, the fluids and tissues possess bactericidal 

 properties. Thus, the serum of the rabbit vaccinated 

 against the pyocyanic disease, is bactericidal for the 

 microbe of this disease; but this property also be- 

 longs to the solid tissues of the vaccinated animals, a 

 fact which has been further demonstrated by the fail- 

 ure of attempts to cultivate the bacillus of symptom- 

 atic charbon in the thigh of a guinea pig vaccinated 

 against this aflectiou. The production of the bacteri- 

 cidal state by vaccination is established for a certain 

 number of germs : the bacillus of bacteridian char- 

 bon, symptomatic charbon, blue pus, the vibrio of 

 cholera, and Metschnikofi''s vibrio. 



This property is communicated to the vaccinated 

 animal by the mingling of the vaccinating substances 

 with the nutritive liquids of the economy ; the con- 

 tact of these fluids with the tissue elements brings 

 about a permanent nutritive modification of the lat- 

 ter; this modification, throughout all the time of the 

 duration of the immunity, exerts its influence upon the 

 fluids of the body, endowing them with the microbi- 

 cidal faculty. By virtue of this faculty the virulent 

 germs against which the vaccination has been directed, 

 when they attempt to invade the organism, find them- 

 selves opposed, attenuated, through contact with the 

 fluids, their secretion products which tend to diminish 

 diapedesis are less abundantly produced and the phag- 



