MANUAL OF VACCINATION.
The object of Vaccination.
1. The object of vaccination, it is well known, is to give immunity from
small-pox. So marvellous a change has it produced within the last half
century, that there are many now to whom small-pox is only a name, and
who, having never seen this loathsome disease or realized its baneful results,
can with difficulty understand the urgent necessity of vaccination. It is
impossible in words to convey adequately to those persons the full extent
of the mischief which small-pox works among the unprotected, but it may
be said that nearly half of the unvaccinated, who are attacked, die, and of
those who survive the larger proportion are disfigured for life or maimed by
the loss of one or both eyes, or crippled by injuries to their joints. Very
few unvaccinated people are naturally immune to small-pox, which is one of
the most highly contagious diseases known, and spares neither childhood,
youth nor age.
Cow-pox in the cow.
2. Cow-pox (vaccinia) is modified small-pox (variola), i.e. it is small-pox
modified by passage through the cow. Jenner believed this, and it was long
disputed; but Ceely and Badcock inoculated cows with small-pox virus in
1840 and produced pustules at the seat of inoculation (true cow-pox). In-
oculation with the contents of these pustules successfully protected cows
from cow-pox and human beings from small-pox. In the report of the Royal
Vaccination Commission (1896) this point was extensively gone into, and the
conclusion arrived at was, that the body of the cow has the power to convert
small-pox matter into vaccine lymph (see final report of the Royal Com-
mission on Vaccination, dated September 18th, 1896). Cows only and not
oxen, are subject to cow-pox, and the original contagion was derived from
human beings, the subjects of small-pox, in the process of milking. Cow-pox
never occurs spontaneously in man and is communicable to the latter by
inoculation of its own specific virus. Vaccinia, therefore, is true variola
modified by " cultivation " in the cow, and is the first, and hitherto the most
successful, example of the method of protection from specific diseases by
previous inoculation with an attenuated virus.
Discovery of Vaccination.
3. The practice of vaccination—the greatest triumph of medicine—was
the achievement of Dr. Jenner, an English physician. In 1798, upwards of
one hundred years ago, his attention was directed to the fact that the milk-
maids in the dairy farms of Gloucestershire were subject to pustular
eruptions on the fingers, similar in every respect to that seen on the udders
of cows. The belief was prevalent among the country people that those
suffering from such an eruption did not catch small-pox. He inoculated a
boy with matter from a cow's udder, and thus discovered that lymph taken
from the vesicles on the udders and teats of cows suffering from cow-pox,
when inserted into the arm of a human being, produced in the course of a
few days a vesicle nearly similar to that on the teats of the cow; and that
lymph taken from that vesicle and inserted into the arm of another human
being was followed by a similar result, and so on, from one individual
to another ad infinitum. Individuals so operated upon were, he found,