He began testing a number of compounds against different microbes. It was during his research that he coined the terms "chemotherapy" and "magic bullet". Although he used the German word zauberkugel in his earlier writings, the first time he introduced the English term "magic bullet" was at a Harben Lecture in London in 1908.[1] By 1901, with the help of Japanese microbiologist Kiyoshi Shiga, Ehrlich experimented with hundreds of dyes on mice infected with trypanosome, a protozoan parasite that causes sleeping sickness.