652 APPENDIX. 



appearance. With hsematoxylin (Dela field's) and eosin 

 the nucleus of the epithelial cells take an irregularly 

 granular, dark purple stain, while the peculiar bodies 

 are a fainter, homogeneous purple, and the cell-bodies 

 pink" (Fig. 87). 



Horses, rabbits, and sheep were successively vaccin- 

 ated with calf vaccine, but in none was the take any- 

 where as good as in calves, nor did it occur in every 

 instance. Guinea-pigs and dogs failed to take in a 

 few trials. The pulp and serum obtained from an 

 epidemic of cowpox took feebly in calves in a moder- 

 ate percentage of those inoculated. The characteristic 

 vaccine bodies were found practically identical with 

 those in vaccinia, except the bodies were a little larger 

 and more irregular in outline. 



The Preparation of Vaccine. For the following sug- 

 gestions I am indebted to Dr. J. H. Huddleston, who 

 has had the immediate charge of the production of 

 vaccine for the New York Health Department for 

 some years : 



Seed Virus. A sufficient amount of vaccine virus 

 should be on hand to vaccinate forty to fifty persons. 

 Five children in good health, and not previously vac- 

 cinated, should then be vaccinated each in a spot the 

 size of a ten-cent piece. On the fifth day after vaccin- 

 ation the top of the resulting vesicle should be removed 

 and sterilized bone slips be rubbed on the base exposed. 

 It should be possible in this manner to charge at least 

 from one to two hundred slips on each side of the slip 

 from each child. The slips should be allowed a moment 

 to dry and then placed in a sterilized box, in which, if 

 kept in cold storage, they will probably remain efficient 

 at least two or three weel^s. 



