During the Massacre, the Japanese did a vast project to develop weapons of biological warfare, including plague, anthrax, cholera and a dozen other pathogens. It was a gigantic research focused on biological weapons. Humans were used as guinea pigs, known as "logs".
These "logs" were used in all sorts of experiments. Some, being infected purposely with a plague as part of a research project,
were cut open from the chest to the stomach to see what the disease does to the man's insides. Anesthetics were never used, out of concern that it might have an effect on the results. The vivisection was routinely used for practicing various kinds of surgery. First an appendectomy, then an amputation of an arm and finally a tracheotomy. When the Japanese finished practicing, they killed the patient with an injection.
Medical researchers also locked up diseased prisoners with healthy ones, to see how readily various ailments would spread. The doctors put others inside a pressure chamber to see how much the body can withstand before the eyes pop from their sockets.
To determine the treatment of frostbite, prisoners were taken outside in freezing weather and left with exposed arms, periodically drenched with water, until the frozen arm emitted a sound resembling that which a board gives when it is struck.
The doctors even experimented on children, including a three-day-old baby, measuring the temperature with a needle stuck inside the infant's middle finger to keep it straight to prevent the baby's hand clenching into a fist.
Sheldon H. Harris, a historian at California State University in Northridge estimates that more than 200,000 Chinese were killed in germ warfare field experiments. Then, as the war was ending, the Japanese purposely released all the plague-infected animals. The Northeastern China immediately became a disaster area and caused outbreaks of the plague that killed at least 30,000 people from 1946 through 1948.