652 APPENDIX. 
appearance. With hematoxylin (Delafield’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 weeks. 
