PROPHYLACTIC IMMUNIZATION OR VACCINATION 



631 



Cross-scarification, which is forbidden in Germany, favors the growth of 

 anaerobic bacteria under the crust that forms on the surface of the 

 abrasion where the resistance is lowered by the action of the virus. 

 The circular scarification gives more control over the dosage, and there 

 is no tendency to the development of excessively sore areas. 



FIG. 128. METHOD OF VACCINATION AGAINST SMALLPOX. 



The skin is stretched, and a series of superficial and parallel scratches made through 

 the epidermis with a sterilized needle. 



Usually one inoculation of the virus is sufficient, but in times of 

 threatened epidemic two or more inoculations are made at the same time, 

 not only to insure a successful result, but rapidly to immunize the 

 patient. It would appear that the degree of immunity bears some rela- 

 tion to the number or size of the vaccination lesions, and this can readily 

 be understood if the infection is local and the body-cells are stimulated 

 by a diffusible toxin. If, however, the vaccination lesion is but the 



