630 ACTIVE IMMUNIZATION 



tional samples are purchased in the open market in different parts of the 

 country. All these are subjected to a vigorous bacteriologic examina- 

 tion, especially for tetanus bacilli, by a laboratory worker who devotes 

 all his time to this work. The federal regulations require each vaccine 

 institute to perform a careful autopsy on each calf after the vaccine 

 virus has been removed, and if any communicable disease is found or 

 suspected in the animal, the virus must not be placed on the market, 

 but must be destroyed. In accordance with this law, permanent records 

 of the bacteriologic examinations of the virus and of the autopsy shall 

 be kept in each institute. 



Technic of Vaccination. The essential part of the process of vac- 

 cination is that the virus should be introduced through the epidermis 

 so as to be absorbed by the lymphatics and blood-vessels of the corium. 



The site usually chosen is the skin of the outer side of the upper arm, 

 over the insertion of the tendon of the deltoid muscle. Sometimes, in 

 females, the outer side of the thigh or well above the knee on the inner 

 aspect of the thigh is used. Vaccination on the leg, however, is never 

 advisable, as it would appear that such vaccinations are more prone 

 to take on an excessive inflammatory action owing to the greater con- 

 gestion due to the dependent position of the lower extremities; there 

 is also more likelihood of secondary infection and mechanical violence 

 occurring. 



The skin is washed with alcohol and finally with water and then 

 dried, care being exercised not to rub too vigorously; if the skin is 

 reddened, it is best to wait until the hyperemia subsides. Grasp the 

 arm with the left hand, rendering the skin tense, and with a sterile 

 needle or scalpel carefully remove the epidermis over a square area 

 measuring about one-eighth of an inch (Fig. 128). Bleeding should be 

 avoided an abraded surface that just oozes serum is especially to be 

 desired. The virus is then expressed or placed upon this area (never 

 blown out), and thoroughly rubbed in with a sterilized wooden tooth-pick 

 or the vaccine point. After allowing the lymph to dry, a light sterile 

 gauze dressing should be applied. 



Some operators abrade through the lymph ; others make one or two 

 straight lines of scratches and rub in the virus. 



Another excellent method 1 consists in abrading the arm with a light 



rotatory motion of a von Pirquet chisel (sterilized in alcohol and in a 



flame), measuring about 2 mm. in width. (See Fig. 122.) The virus 



is then applied, and thoroughly rubbed in with a sterile tooth-pick. 



1 Force, J. N.: Jour. Amer. Med. Assoc., 1914, Ixii, 1466. 



