The accounts are wrenching to read even after so much time has passed: a Russian mother and daughter left in a gas chamber, for example, as doctors peered through thick glass and timed their convulsions, watching as the woman sprawled over her child in a futile effort to save her from the gas. The Origins Ban on Weapon Entices Military

Japan's biological weapons program was born in the 1930's, in part because Japanese officials were impressed that germ warfare had been banned by the Geneva Convention of 1925. If it was so awful that it had to be banned under international law, the officers reasoned, it must make a great weapon.

The Japanese Army, which then occupyied a large chunk of China, evicted the residents of eight villages near Harbin, in Manchuria, to make way for the headquarters of Unit 731. One advantage of China, from the Japanese point of view, was the availability of research subjects on whom germs could be tested. The subjects were called marutas, or logs, and most were Communist sympathizers or ordinary criminals. The majority were Chinese, but many were Russians, expatriates living in China.

Takeo Wano, a 71-year-old former medical worker in Unit 731 who now lives here in the northern Japanese city of Morioka, said he once saw a six-foot-high glass jar in which a Western man was pickled in formaldehyde. The man had been cut into two pieces, vertically, and Mr. Wano guesses that he was Russian because there were many Russians then living in the area.

The Unit 731 headquarters contained many other such jars with specimens. They contained feet, heads, internal organs, all neatly labeled. "I saw samples with labels saying 'American,' 'English' and 'Frenchman,' but most were Chinese, Koreans and Mongolians," said a Unit 731 veteran who insisted on anonymity. "Those labeled as American were just body parts, like hands or feet, and some were sent in by other military units."

There is no evidence that Americans were among the victims in the Unit 731 compound, although there have been persistent but unproven accusations that American prisoners of war in Mukden (now Shenyang) were subject to medical experimentation.

Medical researchers also locked up diseased prisoners with healthy ones, to see how readily various ailments would spread. The doctors locked others inside a pressure chamber to see how much the body can withstand before the eyes pop from their sockets.