Vaccination, vak-si-na'shun, the act of giving a person an infectious disease known as cowpox. Another name for the disease is vaccinia, from the Latin vacca, a cow. The operation is performed usually by scraping away the outer skin of the arm or thigh and applying a small amount of virus or lymph taken directly from a diseased cow or from the scab of a person who has been freshly vaccinated. Vaccinia or cowpox is, it is thought, a mild or degenerate form of the dread disease, smallpox. When a person's arm has been vaccinated the spot turns red in a day or two. On the third or fourth day a sort of blister appears, followed at the end of the eighth day by a ring of inflammation. In about twelve days from the beginning the inflammation begins to subside and the blister turns yellow and then dries up and forms a crust or scab which usually falls off at the end of twenty days, leaving a permanent scar. During this interval the patient has mild symptoms of smallpox. The purpose of vaccination is to accustom the system to an attack of this sort, and render it proof against smallpox. In some way not understood by science the lymph of the body fortifies itself during this mild sickness in such a way that the germs of smallpox cannot live in the body should they unfortunately be taken into the blood at a later date. The history of vaccination is full of interest. Cowpox attacks many animals of the ox kind, but particularly a milking cow. The blisters, like those of vaccination, form around the teats. Towards the end of the eighteenth century the notion got abroad in the dairy district of western England that milkmaids and others who had caught the cowpox in their hands or arms by milking cows were exempt from the smallpox from which their relatives died. This theory attracted the attention of Edward Jenner, a young medical student, who saw in it a promising means of averting the dreadful scourge of smallpox. In 1778 he laid his observations before the medical profession. Disregarding the universal ridicule with which his views were met, he published in 1796 a now celebrated treatise on the causes and effects of cowpox. His views could no longer be ignored. They have been the subject of bitter controversy from that time until the present day. Not to go into detail, the whole theory of vaccination lies in the simple principle that one who has had cowpox is not likely to take the smallpox. Many mistakes have been made in vaccinating. Persons have been vaccinated who were not in physical condition to withstand even the mild cowpox. Blundering in the use of virus has resulted in the communication of smallpox itself and in the death of many patients; but in general it may be said that a contest running through a hundred years has been decided in favor of vaccination. The chances of death from vaccination itself have been reduced to a minimum. The official records of Germany covering 32,000,000 cases, show that deaths from cowpox amount to but two per million vaccinations. The low death rate from smallpox in countries that have enforced vaccination affords a strong proof of its value. Stated in the number of deaths per year for every million people, in London, where records reach back to 1629, the annual death rate from smallpox has fallen from over 4,000 people per million to less than twenty. In Prussia the rate of deaths was quite as high, but, under strict enforcement of vaccination laws, the death rate has fallen to two per million. At the beginning of the nineteenth century the annual death rate in Sweden from smallpox was over 2,000 per million people. In 1816 vaccination was made compulsory; the death rate fell to 133 inside of ten years, and the century closed with an annual death rate from smallpox not exceeding one person per million inhabitants. Austria, Italy, India, Australia, Japan, in short, all progressive countries, add their testimony in favor of vaccination as a preventive of smallpox. While there is no general law in the United States, immigrants are vaccinated before they are allowed to land. Army surgeons enforce vaccination among the soldiers, and most if not all states permit local boards of education to require vaccination as a condition of attending school. There are in the United States a number of institutions that make a regular business of supplying the cowpox virus or vaccine. It is cultivated usually on the body of heifer calves, and is shipped to physicians in glass tubes. There is still, it must be confessed, some opposition even from physicians to the practice of vaccination, but in the face of what it has done for the world the merits of Jenner's great discovery cannot be denied successfully. See JENNER; SMALLPOX; PASTEUR; HYDROPHOBIA.