Vaccination

[U. vacca, a cow.] Jcuuer in 1796 noticed that persons who had much to do with cows, and who had caught from these animals a mild disease known as cow-pox, did not after¬ wards catch small-pox. The lymph by which the cow-pox is transmitted is a clear fluid obtained from a cow or a calf, or from the swelling on the arm of a vaccinated person. This lymph is intro¬ duced into the body by scratching the arm and then rubbing into the blood the lymph from little gla tul3es.