SMALLPOX 661 



animals can not lick the scarified surfaces. Careful veterinary control 

 before vaccination and during the period of treatment must be observed 

 in order to eliminate animals with systemic disease or other complications. 



The calves may be vaccinated with material taken from previously 

 vaccinated animals. Again, they may be inoculated with "seed virus" 

 obtained from the vesicles of human vaccinia. This method of using 

 humanized virus for the inoculation of calves for vaccine production is 

 preferred by many workers and is spoken of as "retro vaccination." 



Park l believes that the most efficient and reliable seed virus consists 

 of what he calls human-calf-rabbit seed virus. Crusts from healthy 

 children, 19 days after vaccination, are collected. These are cut up and 

 emulsified with boiled water. With this an area of about 6 inches square 

 on a calf, the remainder of which is vaccinated the ordinary way, is in- 

 oculated. The virus from this space is separately collected and, after 

 being glycerinated, is used in dilution of 1 to 12J^ parts of salt solution 

 to vaccinate rabbits on the shaven skin of the back. The pulp from this 

 rabbit vaccination is then used for calf vaccination. 



Actual vaccination of the animals is done as follows: Calves which 

 have been kept under observation for at least a week are thoroughly 

 washed and cleaned and the abdomen is clipped and shaved over an area 

 extending from the ensiform cartilage to the pubic region, including 

 the entire width of the belly and the inner folds of the thighs. It is 

 best to shave the animal a day or two before vaccination so as to avoid 

 fresh scratches and excoriations. Just before actual operation the 

 animal is strapped to a specially constructed operating table in such a 

 way as to allow free access to the shaved area. This area is now thor- 

 oughly washed with soap and water followed by alcohol, or, in some 

 institutes, by a weak solution of lysol. If the latter is used, the field 

 of operation must again be thoroughly rinsed with sterile water. About 

 a hundred small scarifications are made in this area, preferably by 

 crossed scratches, covering for each scarification an area of about 3-4 

 square centimeters. Into these areas the virus is rubbed, using for each 

 small area a quantity about sufficient to vaccinate three children. Two 

 to three centimeter spaces are left between the lesions. The lesions are 

 then allowed to dry and may be covered with sterile gauze or, as in 

 Vienna, 2 with a paste made up of beeswax, gum arabic, zinc oxid, water, 

 and glycerin. In some institutes the lesions are left entirely uncovered. 



Ordinarily within about twenty-four hours after vaccination a narrow 

 pink areola appears about the scratches. Within forty-eight hours the 

 1 Park and Williams, Path. Microorg., N. Y., 1914, p. 569. 2 Paul, loc. cit. 



