6 
JXEVITABLE mPURITIES IX BOTIXE VACCIXE VIEUS. 
Vaccinia is a specific disease, the cause of which has not been deter- 
mined. We are, therefore, working somewhat in the dark. We are 
compelled to vaccinate our patients with a virus containing micro- 
organisms other than those causing vaccinia. The importance of using 
a virus as pure as possible need not be emphasized here, for we do not 
want to inoculate our patients with any other infection than the one 
which protects the individual against smallpox. On account of this 
danger human virus has been discarded in many countries, despite the 
fact that human virus is believed to be superior to bovine virus so far as 
the reliability and the duration of its immunizing power are concerned. 
The production of bovine virus by propagating it from heifer to 
heifer is credited to Vegri, of Xaples, about 18d2. It took some years 
for the advantages of this virus to be appreciated. Practically no 
other kind is now used in the large communities of Europe and in our 
own country. The great advantage of bovine virus, in addition to the 
ease with which it may be procured, is that it absolutely eliminates the 
possibility of the transmission of syphilis and other infections peculiar 
to the human family. 
Now, although bovine virus is free from the danger of conveying 
the infectious diseases peculiar to man, it is liable to other equally 
undesirable contaminations. For instance, in addition to the micro- 
organisms that are specific for vaccinia, it contains the ]ius cocci and 
the bacteria that live normally upon and in the skin of the calf, and 
these micro-organisms always contaminate bovine virus. It is impos- 
sible to use germicidal agents in the treatment of the vaccinal eruption 
of calves, as such substances would kill the potency of the virus. 
Therefore, it is evident that ev^n the greatest care will not insure 
such virus against ’•foreign" organisms. 
G o o 
OB.JECT OF GLTCERIXATIXG THE VACCIXE PULP. 
In order to eliminate the danger of the contaminating bacteria, Dr. 
Moncton Copeman, in 1891, devised the method of mixing the pulp 
with sterile glycerin of first quality. The advantages which Copeman 
claimed for the glycerin were that it not only prevented the growth 
and multiplication of the bacteria, always found in bo\fine virus, but 
gradually ‘destroyed those which were present. 
Glycerin can hardly be dignified with a place among the germicides, 
although the object of adding it to vaccine ifirus is to destroy the con- 
taminating micro-organisms. Bacteria are slowly killed by glycerin, 
just as they are killed by drying; the glycerin is supposed to produce 
its bactericidal efiects by a process of slow dehydration. Germs with 
thick envelopes resist it indefinitely. It has no action upon endoge- 
nous spores at all; in fact, it is a preservative of such infections as 
