654 APPENDIX. 



Collection. On the fifth or sixth day, depending upon 

 the rate of development of the vaccine vesicles, they 

 should be ready for collection. The entire shaved area 

 is washed with sterile water and sterile cotton, and the 

 crusts are picked off. The soft, pulpy, remaining mass 

 is then curetted off with an ordinary steel curette and 

 the pulp placed in a sterilized vessel. After the curet- 

 tage serum exudes from the torn base of the vesicle, 

 and ivory slips may be charged in this. The pulp 

 should be mixed with from two to three times its 

 weight of glycerin and water, equal parts, and this is 

 done most effectively by passing the mixture between 

 the rollers of a Doring mill. A watery pulp, especially 

 if it is not to be used immediately, should have the 

 smaller proportion of glycerin. The emulsion so pro- 

 duced can then be put up for issue in vials. The slips 

 charged with the serum from the calf may also be used 

 for vaccinating. Capillary tubes require especial means 

 of filling, and small vials filled and corked answer the 

 purpose admirably. 



Propagation. Subsequent animals may be vaccinated 

 in any one of the three ways: (a) Slips may be charged 

 from typical vesicles on primary vaccinations, just as 

 with the first calf, and used for seed virus; (6) slips 

 charged with the serum from the calf may be used to 

 vaccinate a second calf; (c) the glycerinated emulsion 

 may be used to vaccinate succeeding calves, but in the 

 last case it is necessary to keep the emulsion a varying 

 length of time often two or three months before it 

 is fit for use to vaccinate the calf, because the use of 

 fresh glycerinated pulp on a succession of calves leads 

 to prompt degeneration of the vaccine and to the pro- 

 duction of infected vesicles. 



