To dehumanize prisoners in their minds, the scientists of Unit 731 called their test subjects "Marutas" or logs. Unit 731 faculty's observation of Marutas included their reaction to bubonic plague, typhoid, paratyphoid A and B, typhus, anthrax, smallpox, tularemia, infectious jaundice, gas gangrene, tetanus, cholera, dysentery, glanders, scarlet fever, undulant fever, tick encephalitis, "songo" or epidemic hemorrhagic fever, whooping cough, diphtheria, pneumonia, erysipelas, epidemic cerebrospinal meningitis, venereal diseases, tuberculosis, salmonella, frostbites, and many more deadly viruses, germs, and bacteria. To observe the real-time effects of these harmful agents, these prisoners were often subject to vivisections without the use of anesthesia. In the case where a human experimental subject was exhausted from the experiments, they were to be killed one way or another. Some test subjects were handed potassium cyanide tablets, while others ingested porridge with heroin.

from https://www.pacificatrocities.org/marutas-of-unit-731-guide.html