VACCINATION AGAINST SMALL-POX 69 



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dose varies with the stage of the disease; 5 c.c. is an effective pro- 

 phylactic dose, while from 20 to 300 c.c. have been used often as 

 curative doses. 



VACCINATION. 



By the use of attenuated, or killed micro-organisms, it is possible 

 to effectively vaccinate men and animals against many diseases, 

 notably, small-pox, hydrophobia, plague, cholera, typhoid fever, 

 anthrax and quarter-evil. 



Any of the bacterial products used as prophylactics are sometimes 

 called vaccines, the word being borrowed from small-pox vaccine. 

 It is better to use the word bacterin for the purpose, even when they 

 are given prophylactically. Bacterin is employed for the dead 

 bacterial masses used therapeutically. 



Vaccination Against Small-pox. 



There is now no doubt that vaccinia or cow-pox is but modified 

 small-pox in the cow. The causal agent of small-pox, through its 

 life in the tissues of the cow, becomes so modified that it does not 

 produce in man variola, but vaccinia. This causal agent is believed 

 to be a protozoan, called by its discoverers Cytoryctes variola. 



By the term vaccination, in its strict sense, we mean the applica- 

 tion of attenuated small-pox virus, weakened by passage through 

 kine, to human beings and infecting them with the modified disease. 

 The disease is localized at first at the site of inoculation, and a bleb 

 or vesicle forms. As a rule the disease does not become generalized. 

 It creates, in the vaccinated individual, an active immunity against 

 small-pox. The toxins diffused through the blood-stream stimulate 

 the cells of the body into forming either anti-toxic bodies, or anti- 

 body substances. 



These various substances, as yet unknown, remain for along 

 period within the body of the vaccinated person and may protect it 



