to explode hundreds of feet above ground and shower infected fleas over Chinese cities. Initially the Uji bomb was made of a steel casing but this proved inadequate as very few pathogens survived the heat generated by the initial explosion, therefore General Ishii modified the bomb to use a ceramic casing in place of the steel frame. These new Uji bombs were tested in Ping Fan airfields on human subjects, and were used to infect large areas with various pathogens. Unit 1644 Japanese military unit 1644 was headed by Masuda Tomosada, who was appointed by General Shiro Ishii. Unit 1644 was established in 1939 in Japanese-occupied Nanking. The unit operated under the guise of the Epidemic Prevention and Water Purification Department, and its main function was the mass production of bacteria to be used for attacks; it also conducted experiments with various biological agents. Unit 1644 focused mainly on carrying out experiments with cholera, typhus, and bubonic plague. The unit also experimented with various poisons extracted from animals, such as Taiwanese snake poisons from the cobra, hadi, and amagasa snakes. Unit 1644 was relatively small when compared with other units in the Japanese biological weapons program, but received large amounts of funding despite its relatively small size. Impact of the attack The Kaimingjie germ weapon attack consisted of corn and cloth infested with fleas. These fleas, infected with cholera and the bubonic plague, were airdropped over the area of Ningbo on October 27, 1940. Rats would be infected with these fleas; the fleas would then move on and find human hosts. On October 29 the first three cases of the plague were diagnosed by local health officials in Kaimingjie. An estimated 26 deaths had occurred by November 2. In response to the situation, quarantines were imposed on affected areas and homes were routinely disinfected. Sheets and cloths were burnt as a precautionary measure and vaccinations were soon introduced by officials. The areas of the city most affected by the attack were evacuated and later burnt to prevent further outbreaks and completely eradicate the disease. One victim, Jiand Chun Geng, suffered flesh-eating ulcers. Others suffered untreated infections that led to death. There were also many casualties leading up to this attack. In particular, Unit 731's experiments saw many victims. Dr. Sheldon Harris estimated that from testing of prototype weapons, 250,000 civilians died. There was a second Japanese attack on Kaimingjie that