626 ACTIVE IMMUNIZATION 



periments, that vaccination will protect monkeys against subsequent 

 inoculation with smallpox virus, and this completely confirms the early 

 experiments of Jenner and others who proved the efficacy of vaccination 

 by the "variolous test." 



The Preparation of Cowpox Vaccine. During the early days of 

 vaccination it was customary to inoculate human beings with material 

 obtained from the pustules of those previously vaccinated. The old- 

 time physician carefully removed choice scabs and carried them about 

 in a special case ready for inoculation. While this method served its 

 purpose well, there were several drawbacks to its use, the chief of which 

 was the danger of transmitting syphilis. It has now for many years 

 been the custom to use virus obtained from animals, the production of 

 which can be carefully controlled and tested, any danger of transmitting 

 syphilis being thus obviated, because the heifer or cow used in the pre- 

 paration of the virus is not subject to this disease. The opponents to 

 vaccination, however, persist in using old and obsolete statistics regard- 

 ing the transmission of syphilis to support their claims, although these 

 have absolutely no bearing upon the modern methods of preparing the 

 virus. 



Seed Virus. This refers to the virus for vaccinating the calves or 

 other animals used, and is a most troublesome factor to those engaged 

 in this work. According to Park and Huddleston, a sufficient amount of 

 vaccine virus should be on hand to vaccinate from 40 to 50 persons. 

 Five children in good health and not previously vaccinated should then 

 receive an inoculation, each spot being of the size of a ten-cent piece. 

 On the fifth day after vaccination the upper layer of the resulting vesicle 

 should be removed, and sterilized bone slips be rubbed on the base thus 

 exposed. From 100 to 200 slips on each side of the slip may be charged 

 from each child. The slips should be allowed to dry for a minute, and 

 should then be placed in a sterilized box and preserved in cold storage, 

 where they will remain active for at least two or three weeks. The 

 aforenamed observers now use rabbits alternately to obtain seed virus. 



Subsequent animals are vaccinated with any one of three vaccines 

 (1) Slips charged from typical vesicles of a calf; (2) slips charged with 

 the serum from a calf after removal of the vesicles; (3) the glycerinated 

 virus may be used to vaccinate succeeding calves, but in this case it is 

 necessary to keep the glycerinated virus for two or three months, since 

 the use of fresh virus on a succession of calves leads to prompt degenera- 

 tion of the vaccine and to the production of infected vesicles. 



The New York Vaccine Laboratory produces a virus that is never 



