Editing Unit 731 (section)

== Experiments ==
{{Shōwa Statism|Atrocities}}
The military police and the Special Services Agency were responsible for finding victims to be test subjects for the unit, while a group of physicians were responsible for maintaining healthy victims and dispatching them for experimentations.<ref name="Indiana University Press"/> Not all individuals sent to Unit 731 underwent experiments; these experiments were reserved for healthy individuals, and once accepted into the program, the preservation of their health became a top priority.<ref name="Indiana University Press"/>

Human experiments involved intentionally infecting captives, especially Chinese prisoners of war and civilians, with disease-causing agents and exposing them to bombs designed to disperse infectious substances upon contact with the skin. There are no records indicating any survivors from these experiments; those who did not die from infection were murdered for autopsy analysis.<ref name="United States Responses to Japanese"/> After human experimentations, researchers commonly used either [[potassium cyanide]] or [[chloroform]] to kill survivors.<ref>{{cite book |last1=LaFleur| url=https://books.google.com/books?id=gGQYOvo9-AsC&q=Yoshimura+ |first1=William |last2=Böhme |first2=Gernot |last3=Shimazono |first3=Susumu |title=Dark medicine: rationalizing unethical medical research |date=2007 |publisher=Indiana University Press|page=75 |location=US| isbn=978-0-253-22041-7 }}</ref>

According to American historian [[Sheldon H. Harris]]:
<blockquote>The Togo Unit employed gruesome tactics to secure specimens of select body organs. If Ishii or one of his co-workers wished to do research on the human brain, then they would order the guards to find them a useful sample. A prisoner would be taken from his cell. Guards would hold him while another guard would smash the victim's head open with an ax. His brain would be extracted off to the pathologist, and then to the [[crematorium]] for the usual disposal.<ref>{{Cite book |last=Harris |first=Sheldon H. |url=https://archive.org/details/factoriesofdeath0000harr/page/28 |title=Factories of death: Japanese biological warfare 1932 - 45 and the American cover-up |date=1999 |publisher=Routledge |isbn=978-0-415-13206-0 |edition=Reprint |location=London |pages=28}}</ref></blockquote>

Nakagawa Yonezo, [[professor emeritus]] at [[Osaka University]], studied at [[Kyoto University]] during the war. While he was there, he watched footage of human experiments and executions from Unit&nbsp;731. He later testified about the playfulness of the experimenters:<ref>{{cite book|last1=Gold|first1=Hal|title=Japan's Infamous Unit 731: First-hand Accounts of Japan's Wartime Human Experimentation Program |year=2019|publisher=Tuttle Publishing|isbn=978-0804852197|page=222|last2=Totani|first2=Yuma.}}</ref>

<blockquote>Some of the experiments had nothing to do with advancing the capability of [[Biological warfare|germ warfare]], or of medicine. There is such a thing as professional curiosity: 'What would happen if we did such and such?' What medical purpose was served by performing and studying beheadings? None at all. That was just playing around. Professional people, too, like to play.</blockquote>

Prisoners were injected with diseases, disguised as [[Vaccine|vaccinations]],<ref>{{cite news|url=http://www.medicalbag.com/despicable-doctors/pure-evil-wartime-japanese-doctor-had-no-regard-for-human-suffering/article/472462/|title=Pure Evil: Wartime Japanese Doctor Had No Regard for Human Suffering|date=2014-05-28|website=Medical Bag|access-date=2017-03-28|language=en|archive-date=2017-03-29|archive-url=https://web.archive.org/web/20170329140410/http://www.medicalbag.com/despicable-doctors/pure-evil-wartime-japanese-doctor-had-no-regard-for-human-suffering/article/472462/|url-status=live}}</ref> to study their effects. To study the effects of untreated [[venereal disease]]s, male and female prisoners were deliberately infected with [[syphilis]] and [[gonorrhea]], then studied.<ref>{{cite journal | url=https://www.actasdermo.org/en-syphilis-human-experimentation-from-first-articulo-S1578219014002030 | doi=10.1016/j.adengl.2013.09.009 | title=Syphilis and Human Experimentation from the First Appearance of the Disease to World War II: A Historical Perspective and Reflections on Ethics | date=2014 | last1=Cuerda-Galindo | first1=E. | last2=Sierra-Valentí | first2=X. | last3=González-López | first3=E. | last4=López-Muñoz | first4=F. | journal=Actas Dermo-Sifiliográficas (English Edition) | volume=105 | issue=8 | pages=762–767 | doi-access=free | hdl=10486/713606 | hdl-access=free }}</ref> A special project, codenamed ''Maruta'', used human beings for experiments. Test subjects were gathered from the surrounding population and sometimes euphemistically referred to as {{nihongo|"logs"|丸太|maruta}}, used in such contexts as "How many logs fell?" This term originated as a joke on the part of the staff because the official [[Cover-up|cover story]] for the facility given to local authorities was that it was a [[lumber mill]]. According to a junior uniformed civilian employee of the Imperial Japanese Army working in Unit&nbsp;731, the project was internally called "Holzklotz", from the German word for log.<ref>{{cite book |last1=Cook |first1 = Haruko Taya |last2=Cook |first2 = Theodore F. |title = Japan at war: an oral history |edition=1st |year=1992 |publisher = New Press |location = New York |isbn=1565840143 |page=162 }}</ref> In a further parallel, the corpses of "sacrificed" subjects were disposed of by [[Cremation|incineration]].<ref name=":0">{{cite news |url = https://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html?pagewanted=all |title = Unmasking Horror – A special report. Japan Confronting Gruesome War Atrocity |newspaper = The New York Times |date = 17 March 1995 |access-date = April 10, 2017 |archive-date = January 20, 2018 |archive-url = https://web.archive.org/web/20180120034658/http://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html?pagewanted=all |url-status = live |last1 = Kristof |first1 = Nicholas D. }}</ref> Researchers in Unit&nbsp;731 also published some of their results in [[peer-reviewed journal]]s, writing as though the research had been [[Nonhuman primate experimentation|conducted on nonhuman primates]] called "Manchurian monkeys" or "long-tailed monkeys".<ref>{{Cite book |last=Harris |first=Sheldon H. |url=https://archive.org/details/factoriesofdeath0000harr/page/63 |title=Factories of death: Japanese biological warfare 1932 - 45 and the American cover-up |date=1999 |publisher=Routledge |isbn=978-0-415-13206-0 |edition=Reprint |location=London |pages=63}}</ref>

At the age of 14, on the encouragement of a former school teacher, Hideo Shimizu joined the fourth group of minors assigned to Unit 731.<ref name="auto3">{{Cite web|url=https://www.asahi.com/ajw/articles/14988305|title=In twilight years, former Unit 731 member set on spreading truth {{pipe}} The Asahi Shimbun: Breaking News, Japan News and Analysis|work=The Asahi Shimbun }}</ref> He recalled that he was brought to a specimen room where jars of various heights, with some reaching the height of an adult, were stored.<ref name="auto3"/> The jars held body parts from humans preserved in [[formalin]], such as heads and hands.<ref name="auto3"/> There was also a pregnant woman's body with a large belly, where the lower part was exposed to reveal a fetus with hair. Shimizu discovered that the term "logs" was used dehumanizingly to refer to prisoners. He also learned that the prisoners were further dehumanized by being held in facilities referred to as "log cabins".<ref name="auto3"/>

=== Vivisection ===
Thousands of men, women, children, and infants interned at [[prisoner of war camps]] were subjected to [[vivisection]], often performed without [[anesthesia]] and usually lethal.<ref>Nicholas D. Kristof ''New York Times'', March 17, 1995. [https://query.nytimes.com/gst/fullpage.html?res=990CE2D71630F934A25750C0A963958260&sec=health&spon=&pagewanted=print "Unmasking Horror: A special report. Japan Confronting Gruesome War Atrocity"] {{Webarchive|url=https://web.archive.org/web/20110317115032/http://query.nytimes.com/gst/fullpage.html?res=990CE2D71630F934A25750C0A963958260&sec=health&spon=&pagewanted=print |date=2011-03-17 }}</ref><ref name="dissect">{{cite news |title=Dissect them alive: order not to be disobeyed |author=Richard Lloyd Parry |newspaper=Times Online |date=February 25, 2007 |url=http://www.timesonline.co.uk/tol/news/world/asia/article1438491.ece |location=London |access-date=February 26, 2007 |archive-date=May 23, 2011 |archive-url=https://web.archive.org/web/20110523225449/http://www.timesonline.co.uk/tol/news/world/asia/article1438491.ece |url-status=dead }}</ref> In a video interview, former Unit&nbsp;731 member Okawa Fukumatsu admitted to having vivisected a pregnant woman.<ref name="vimeo1">{{cite web |title=(RARE) Unit 731 surgeon Okawa Fukumatsu (interview footage) |url=https://vimeo.com/manage/videos/625179260 |website=(RARE) Unit 731 surgeon Okawa Fukumatsu (interview footage) |access-date=2021-10-07 |archive-date=2021-10-07 |archive-url=https://web.archive.org/web/20211007074509/https://vimeo.com/manage/videos/625179260 |url-status=live }}</ref> Vivisections were performed on prisoners after infecting them with various diseases. Researchers performed [[Minimally invasive procedure#Invasive procedures|invasive surgery]] on prisoners, removing organs to study the effects of disease on the human body.<ref>{{cite web|url=http://www.technologyartist.com/unit_731/ |title=Interview with former Unit 731 member Nobuo Kamada |access-date=February 5, 2004 |url-status=dead |archive-url=https://web.archive.org/web/20061119053825/http://www.technologyartist.com/unit_731/ |archive-date=November 19, 2006}}</ref>

Prisoners had limbs [[amputated]] in order to study [[Blood Loss|blood loss]]. Limbs removed were sometimes reattached to the opposite side of victims' bodies. Some prisoners had their stomachs surgically removed and their [[esophagus]] reattached to the [[Gastrointestinal tract|intestines]]. Parts of organs, such as the brain, lungs, and liver, were removed from others.<ref name="dissect"/> Imperial Japanese Army surgeon [[Ken Yuasa]] said that practising vivisection on human subjects was widespread even outside Unit&nbsp;731,<ref name="nyt">{{cite news |title=Unmasking Horror – A special report. Japan Confronting Gruesome War Atrocity |first=Nicholar D. |last=Kristof |date=17 March 1995 |newspaper=New York Times |url=https://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html?pagewanted=2 |access-date=20 February 2017 |archive-date=7 November 2017 |archive-url=https://web.archive.org/web/20171107115922/http://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html?pagewanted=2 |url-status=live }}</ref> estimating that at least 1,000 Japanese personnel were involved in the practice in mainland China.<ref>{{cite web|url=http://www.japantimes.co.jp/news/2007/10/24/reference/vivisectionist-recalls-his-day-of-reckoning/|title=Vivisectionist recalls his day of reckoning|first=Jun|last=Hongo|date=24 October 2007|via=Japan Times Online|access-date=16 May 2013|archive-date=1 April 2017|archive-url=https://web.archive.org/web/20170401172838/http://www.japantimes.co.jp/news/2007/10/24/reference/vivisectionist-recalls-his-day-of-reckoning//|url-status=live}}</ref> Yuasa said that when he performed vivisections on captives, they were "all for practice rather than for research", and that such practises were "routine" among Japanese doctors stationed in China during the war.<ref name=":0" />

''[[The New York Times]]'' interviewed a former member of Unit 731. Insisting on anonymity, the former Japanese medical assistant recounted his first experience in vivisecting a live human being, who had been deliberately infected with the [[Plague (disease)|plague]], for the purpose of developing "plague bombs" for war. <blockquote>"The fellow knew that it was over for him, and so he didn't struggle when they led him into the room and tied him down, but when I picked up the scalpel, that's when he began screaming. I cut him open from the chest to the stomach, and he screamed terribly, and his face was all twisted in agony. He made this unimaginable sound, he was screaming so horribly. But then finally he stopped. This was all in a day's work for the surgeons, but it really left an impression on me because it was my first time."<ref>{{Cite news |last=Kristof |first=Nicholas D. |date=1995-03-17 |title=Unmasking Horror – A special report.; Japan Confronting Gruesome War Atrocity |language=en-US |work=The New York Times |url=https://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html |access-date=2023-01-03 |issn=0362-4331}}</ref></blockquote>

Other sources provided information on usual practice in the Unit for surgeons to stuff a rag (or medical gauze) into the mouth of prisoners before commencing vivisection in order to stifle any screaming.<ref>{{cite book |last1=Yang |first1=Yanjun |title=Japan's Biological Warfare in China |date=2016 |publisher=Foreign Language Press |location=Beijing |page=13}}</ref>

=== Biological warfare ===
[[File:Building on the site of the Harbin bioweapon facility of Unit 731 関東軍防疫給水部本部731部隊（石井部隊）日軍第731部隊旧址 PB121178a ボイラー楝跡.JPG|thumb|Ruins of a boiler building at the Unit&nbsp;731 [[bioweapon]]s facility]]

Unit&nbsp;731 and its affiliated units ([[Unit 1644]] and [[Unit 100]], among others) were involved in research, development and experimental deployment of epidemic-creating [[biological weapon]]s in assaults against the Chinese populace (both military and civilian) throughout World War&nbsp;II.<ref name="The day the earth died"/>

By 1939, Ishii had condensed his laboratory discoveries to six potent [[pathogen]]s: [[anthrax]], [[typhoid]], [[paratyphoid]], [[glanders]], [[dysentery]], and [[Plague (disease)|plague]]-infected human [[flea]]s. These agents were robust enough to ignite epidemics of considerable magnitude and resilient to aerial dispersal. This marked the initiation of the latter phase of Ishii's elaborate scheme: conducting field trials through military expeditions on unsuspecting civilians, aiming to devise a method of dissemination that would efficiently spread the pathogens in optimal concentrations for maximum devastation. His experiments involved the development of biodegradable bombs housing live rats and fleas infected with diseases, designed to explode mid-air, ensuring the safe descent of the infected creatures to the ground. Additionally, he deployed birds and bird feathers contaminated with anthrax from low-flying aircraft.<ref name="The day the earth died"/>

Plague-infected fleas, bred in the laboratories of Unit&nbsp;731 and Unit&nbsp;1644, were spread by low-flying airplanes over Chinese cities, including coastal [[Ningbo]] and [[Changde]], [[Hunan|Hunan Province]], in 1940 and 1941.<ref name="ciadoc" /> These operations killed tens of thousands with [[bubonic plague]] epidemics. An expedition to [[Nanjing]] involved spreading typhoid and paratyphoid germs into the [[well]]s, [[marsh]]es, and houses of the city, as well as infusing them in snacks distributed to locals. [[Epidemic]]s broke out shortly after, to the elation of many researchers, who concluded that [[paratyphoid fever]] was "the most effective" of the pathogens.<ref>{{Cite book |last=Harris |first=Sheldon H. |url=https://archive.org/details/factoriesofdeath0000harr/page/77 |title=Factories of death: Japanese biological warfare 1932 - 45 and the American cover-up |date=1999 |publisher=Routledge |isbn=978-0-415-13206-0 |edition=Reprint |location=London |pages=77}}</ref><ref name="Barenblatt2004">Barenblatt, Daniel. ''A Plague Upon Humanity: the Secret Genocide of Axis Japan's Germ Warfare Operation'', HarperCollins, 2004. {{ISBN|0060186259}}.</ref>{{Rp|xii, 173}}

The [[Library of Congress]] holds a set of three declassified documents from Unit 731, each more than 100 pages long, translated from Japanese to English. These documents provided comprehensive clinical records about the daily progression of various pathogens within the bodies of helpless prisoners who were experimented on by Japanese doctors.<ref>{{cite book|title=Researching Japanese War Crimes|publisher=National Archives and Records Administration for the Nazi Warcrimes and Japanese Imperial Government Records Interagency Working Group|date=2006|page=17|last=Drea|first=Edward|url=https://www.archives.gov/files/iwg/japanese-war-crimes/introductory-essays.pdf}}</ref>

Japanese soldiers provided testimony indicating that the research program had the capability to manufacture substantial quantities of biological agents on a monthly basis: 300&nbsp;kg of plague, 500–700&nbsp;kg of anthrax, 800–900&nbsp;kg of typhoid, and 1000&nbsp;kg of [[cholera]]. Despite the significant production volumes, even small amounts of these bacteria possessed the potential to cause severe harm and fatalities.<ref name="schulich.uwo.ca">{{Cite journal|last1=Johnson|first1=Kishor|title=A Scientific Method to the Madness of Unit 731's Human Experimentation and Biological Warfare Program|journal=Journal of the History of Medicine and Allied Sciences| url=https://www.schulich.uwo.ca/historymedicine/docs/Johnson_2021_JHMAS_Unit-731_Human-Experimentation.pdf|year=2021|volume=77|issue=1|pages=35–41|doi=10.1093/jhmas/jrab044|pmid=34897467 }}</ref>

Ishii determined that fleas were an efficient carrier for transmitting plague, leading Unit 731 to focus on breeding significant numbers of fleas. To achieve this goal, Unit 731 had approximately 4500 flea incubators, each capable of producing at least 45&nbsp;kg of fleas per cycle. The substantial quantities of plague bacteria and fleas generated, combined with the severe illness and death rates associated with plague infection, illustrate the formidable biological warfare production capabilities wielded by the Japanese. Japanese researchers had the required materials to apply the [[scientific method]] in conducting experiments involving [[inoculation]] and the creation of airborne bacterial bombs.<ref name="schulich.uwo.ca"/>

Food items emerged as the preferred delivery mechanism for bacterial transmission. The unit maintained a stock of uncontaminated fruits. In a specific experiment conducted by Unit 731, typhoid was introduced into melons and cantaloupes. Following the contamination process, the bacterial density was measured. Once reaching a density level, the infected fruit was distributed to a small group of prisoners, with the objective of spreading typhoid throughout the entire group.<ref name="schulich.uwo.ca"/>

Unit 731 conducted biological warfare field trials by attacking many Chinese civilian populations. During the period of 1940 to 1943, Japanese scientists found that using bacterial bombs for transmission was not effective, but they did find success in utilizing planes to spray microorganisms as a means of biological warfare delivery. Unit 100 also deployed aerial spraying methods akin to those examined by Unit 731.<ref name="schulich.uwo.ca"/>

At least 12 large-scale bioweapon field trials were carried out, and at least 11 Chinese cities attacked with biological agents. An attack on [[Changde]] in 1941 reportedly led to approximately 10,000 biological casualties and 1,700 deaths among ill-prepared Japanese troops, in most cases due to cholera.<ref>{{Cite book |last1=Williams |first1=Peter |title=Unit 731: Japan's secret biological warfare in World War II |last2=Wallace |first2=David |date=1989 |publisher=Free Press |isbn=978-0-02-935301-1 |edition=1st American |location=New York |pages=69–70}}</ref> Japanese researchers performed tests on prisoners with [[bubonic plague]], cholera, [[smallpox]], [[botulism]], and other diseases.<ref>[https://fas.org/nuke/guide/japan/bw/ Biological Weapons Program-Japan] {{Webarchive|url=https://web.archive.org/web/20100727172723/http://www.fas.org/nuke/guide/japan/bw/ |date=2010-07-27 }} Federation of American Scientists</ref> This research led to the development of the [[defoliation bacilli bomb]] and the flea bomb used to spread bubonic plague.<ref>[http://www.centurychina.com/wiihist/germwar/731rev.htm Review of the studies on Germ Warfare] {{Webarchive|url=https://web.archive.org/web/20121119074840/http://www.centurychina.com/wiihist/germwar/731rev.htm |date=2012-11-19 }} Tien-wei Wu ''A Preliminary Review of Studies of Japanese Biological Warfare and Unit 731 in the United States''</ref> Some of these bombs were designed with [[porcelain]] shells, an idea proposed by Ishii in 1938.

These bombs enabled Japanese soldiers to launch biological attacks, infecting agriculture, [[reservoir]]s, wells, as well as other areas, with [[anthrax]]- and [[Bubonic plague|plague]]-carrier fleas, [[typhoid]], cholera, or other deadly pathogens. During biological bomb experiments, researchers dressed in protective suits would examine the dying victims. Infected food supplies and clothing were dropped by airplane into areas of China not occupied by Japanese forces. In addition, poisoned food and candy were given to unsuspecting victims. [[Bubonic Plague|Plague]] fleas, infected clothing, and infected supplies encased in bombs were dropped on various targets. The resulting [[cholera]], [[anthrax]], and plague were estimated to have killed at least 400,000 Chinese civilians.<ref>{{cite book |last1=Barenblatt |first1=Daniel |title=A Plague upon Humanity: The Secret Genocide of Axis Japan's Germ Warfare Operation |date=2004 |publisher=Harper |location=New York|isbn=978-0060186258 |pages=[https://archive.org/details/plagueuponhumani00bare/page/163 163–175] |edition=1 |url=https://archive.org/details/plagueuponhumani00bare/page/163 }}</ref> [[Tularemia]] was also tested on Chinese civilians.<ref>[http://ftp.cdc.gov/pub/epr/historyofbt/wmcc/07_tularemia_cc.wmv Video] {{Webarchive|url=https://web.archive.org/web/20170921143738/https://ftp.cdc.gov/pub/epr/historyofbt/wmcc/07_tularemia_cc.wmv |date=2017-09-21 }} adapted from "Biological Warfare & Terrorism: The Military and Public Health Response", [[Centers for Disease Control and Prevention]]. Retrieved October 21, 2007</ref>

Due to pressure from numerous accounts of the biowarfare attacks, [[Chiang Kai-shek]] sent a delegation of army and foreign medical personnel in November&nbsp;1941 to document evidence and treat the afflicted. A report on the Japanese use of plague-infected fleas on Changde was made widely available the following year but was not addressed by the Allied Powers until [[Franklin D. Roosevelt]] issued a public warning in 1943 condemning the attacks.<ref>{{cite web|title=Biohazard: Unit 731 and the American Cover-Up|page=5|url=https://www.umflint.edu/sites/default/files/groups/Research_and_Sponsored_Programs/MOM/b.altheide.pdf|website=[[University of Michigan–Flint]]|access-date=2019-05-31|archive-date=2019-07-31|archive-url=https://web.archive.org/web/20190731012542/https://www.umflint.edu/sites/default/files/groups/Research_and_Sponsored_Programs/MOM/b.altheide.pdf|url-status=dead}}</ref><ref>{{Cite book|last=Guillemin|first=Jeanne|title=One Hundred Years of Chemical Warfare: Research, Deployment, Consequences |chapter=The 1925 Geneva Protocol: China's CBW Charges Against Japan at the Tokyo War Crimes Tribunal |date=2017|editor-last=Friedrich|editor-first=Bretislav|editor2-last=Hoffmann|editor2-first=Dieter|editor3-last=Renn|editor3-first=Jürgen|editor4-last=Schmaltz|editor4-first=Florian|editor5-last=Wolf|editor5-first=Martin|language=en|publisher=Springer International Publishing|pages=273–286|doi=10.1007/978-3-319-51664-6_15|isbn=978-3319516646|doi-access=free}}</ref>

In December 1944, the Japanese Navy explored the possibility of attacking cities in California with biological weapons, known as [[Operation PX]] or Operation Cherry Blossoms at Night. The plan for the attack involved [[Aichi M6A|''Seiran'']] aircraft launched by Sentoku [[I-400-class submarine|submarine aircraft carriers]] upon the West Coast of the United States—specifically, the cities of San Diego, Los Angeles, and San Francisco. The planes would spread weaponized [[bubonic plague]], [[cholera]], [[typhus]], [[dengue fever]], and other pathogens in a biological terror attack upon the population. The submarine crews would infect themselves and run ashore in a suicide mission.<ref>Garrett, Benjamin C. and John Hart. ''Historical Dictionary of Nuclear, Biological and Chemical Warfare'', page 159.</ref><ref>Geoghegan, John. ''Operation Storm: Japan's Top Secret Submarines and Its Plan to Change the Course of World War II'', pages 189–191.</ref><ref>Gold, Hal. Unit 731 Testimony: Japan's Wartime Human Experimentation Program, pages 89–92</ref><ref>{{cite news |last=Kristoff |first=Nicholas D. |date=March 17, 1995 |title=Unmasking Horror -- A special report.; Japan Confronting Gruesome War Atrocity |url=https://www.nytimes.com/1995/03/17/world/unmasking-horror-a-special-report-japan-confronting-gruesome-war-atrocity.html |newspaper=The New York Times |access-date=August 6, 2015 }}</ref> Planning for Operation PX was finalized on March 26, 1945, but shelved shortly thereafter due to the strong opposition of Chief of General Staff [[Yoshijirō Umezu]]. Umezu later explained his decision as such: "If bacteriological warfare is conducted, it will grow from the dimension of war between Japan and America to an endless battle of humanity against bacteria. Japan will earn the derision of the world."<ref>Felton, Mark. ''The Devil's Doctors: Japanese Human Experiments on Allied Prisoners of War'', Chapter 10</ref>

=== Weapons testing ===
Human targets were used to test [[grenade]]s positioned at various distances and in various positions. [[Flamethrower]]s were tested on people.<ref>{{cite journal |last1=Hickey |first1=Doug |last2=Li |first2=Scarllet Sijia |last3=Morrison |first3=Ceila |last4=Schulz |first4=Richard |last5=Thiry |first5=Michelle |last6=Sorensen |first6=Kelly |date=April 2017 |title=Unit 731 and Moral Repair |doi=10.1136/medethics-2015-103177 |journal=Journal of Medical Ethics |volume=43 |issue=4 |pages=270–276|pmid=27003420 |s2cid=20475762 }}</ref> Victims were also tied to stakes and used as targets to test [[Germ warfare|pathogen-releasing bombs]], [[chemical weapon]]s, shrapnel bombs with varying amounts of fragments, and explosive bombs as well as [[bayonet]]s and knives.

{{Blockquote|To determine the best course of treatment for varying degrees of shrapnel wounds sustained on the field by Japanese Soldiers, Chinese prisoners were exposed to direct bomb blasts. They were strapped, unprotected, to wooden planks that were staked into the ground at increasing distances around a bomb that was then detonated. It was surgery for most, autopsies for the rest.|Unit 731, Nightmare in Manchuria<ref>Monchinski, Tony (2008). ''Critical Pedagogy and the Everyday Classroom''. Volumen 3 de Explorations of Educational Purpose. Springer, p. 57. {{ISBN|1402084625}}</ref><ref>Neuman, William Lawrence (2008). ''Understanding Research''. Pearson/Allyn and Bacon, p. 65. {{ISBN|0205471536}}</ref>}}

==== Frostbite testing ====
[[File:Scan Of Yoshimura Hisato's Frostbite Research Data.png|thumb|Scan of [[Yoshimura Hisato]]'s [[frostbite]] research data]]

Army Engineer Hisato Yoshimura<!--Yoshimura is the family name as per http://www.lit.osaka-cu.ac.jp/user/tsuchiya/gyoseki/presentation/UNESCOkumamoto07.html, but this article should generally use Western order for Japanese people.--> conducted experiments by taking captives outside, dipping various appendages into water of varying temperatures, and allowing the [[Frostbite|limb to freeze]].<ref>{{cite web|url=http://www.lit.osaka-cu.ac.jp/user/tsuchiya/gyoseki/presentation/UNESCOkumamoto07.html|title=Self Determination by Imperial Japanese Doctors|website=www.lit.osaka-cu.ac.jp|access-date=2019-05-31|archive-date=2019-05-31|archive-url=https://web.archive.org/web/20190531063454/http://www.lit.osaka-cu.ac.jp/user/tsuchiya/gyoseki/presentation/UNESCOkumamoto07.html|url-status=live}}</ref> Once frozen, Yoshimura would strike their affected limbs with a short stick, "emitting a sound resembling that which a board gives when it is struck".<ref name="Kristor" /> Ice was then chipped away, with the affected area being subjected to various treatments. Military personnel of the Unit referred to Yoshimura as a "scientific devil" and a "cold-blooded animal" due to his strictness and involvement in mass killings and inhumane scientific tests, which included soaking the fingers of a three-day-old child in water containing ice and salt.<ref>{{cite book |last1=LaFleur| url=https://books.google.com/books?id=gGQYOvo9-AsC&q=Yoshimura+ |first1=William |last2=Böhme |first2=Gernot |last3=Shimazono |first3=Susumu |title=Dark medicine: rationalizing unethical medical research |date=2007 |publisher=Indiana University Press|pages=76–77 |location=US| isbn=978-0-253-22041-7 }}</ref>

Naoji Uezono, a member of Unit 731, described in a 1980s interview a grisly scene where Yoshimura had "two naked men put in an area 40–50 degrees below zero and researchers filmed the whole process until [the subjects] died. [The subjects] suffered such agony they were digging their nails into each other's flesh."<ref>{{cite book |last1=Emanuel |first1=Ezekiel |last2=Grady |first2=Christine |last3=Crouch |first3=Robert |last4=Lie |first4=Reidar |last5=Miller |first5=Franklin |title=The Oxford Textbook of Clinical Research Ethics |date=2011 |publisher=Oxford University Press |location=US|page=36}}</ref> Yoshimura's lack of remorse was evident in an article he wrote for the Japanese Journal of Physiology in 1950 in which he admitted to using 20 children and a three-day-old infant in experiments which exposed them to zero-degree-Celsius ice and salt water.<ref>{{cite book |last1=Yoshimura |first1=Hisato |last2=Iida |first2=Toshiyuki |title=Studies on the Reactivity of Skin Vessels to Extreme Cold |date=1950 |publisher=Japanese Journal Of Physiology |location=Japan}}</ref> Although this article drew criticism, Yoshimura denied any guilt when contacted by a reporter from the ''[[Mainichi Shimbun]]''.<ref>{{cite book |last1=Kei-ichi |first1=Tsuneishi |last2=Asano |first2=Tomizo |title=Kieta saikin-sen butai to jiketsu shita futari no igakusha |script-title=ja:消えた細菌戦部隊と自決した二人の医学者|trans-title=The biological warfare unit and two physicians who committed suicide |language=ja |date=1982 |publisher=Shinchosha |location=Tokyo |isbn=9784103440017}}</ref>

Yoshimura developed a "resistance index of frostbite" based on the mean temperature 5 to 30&nbsp;minutes after immersion in freezing water, the temperature of the first rise after immersion, and the time until the temperature first rises after immersion. In a number of separate experiments it was then determined how these parameters depend on the time of day a victim's body part was immersed in freezing water, the surrounding temperature and humidity during immersion, how the victim had been treated before the immersion ("after keeping awake for a night", "after hunger for 24 hours", "after hunger for 48 hours", "immediately after heavy meal", "immediately after hot meal", "immediately after muscular exercise", "immediately after cold bath", "immediately after hot bath"), what type of food the victim had been fed over the five days preceding the immersions with regard to dietary nutrient intake ("high protein (of animal nature)", "high protein (of vegetable nature)", "low protein intake", and "standard diet"), and salt intake (45&nbsp;g NaCl per day, 15&nbsp;g NaCl per day, no salt).<ref>{{cite book |last1=Eckart |first1=Wolfgang |title=Man, Medicine, and the State: The Human Body as an Object of Government Sponsored Medical Research in the 20th Century |date=2006 |publisher=Franz Steiner Verlag |page=191}}</ref> This original data is seen in the attached figure.

==== Syphilis ====
Unit members orchestrated forced sex acts between infected and non-infected prisoners to transmit the disease, as the testimony of a prison guard on the subject of devising a method for transmission of [[syphilis]] between victims shows:

{{blockquote|Infection of venereal disease by injection was abandoned, and the researchers started forcing the prisoners into sexual acts with each other. Four or five unit members, dressed in white laboratory clothing completely covering the body with only eyes and mouth visible, rest covered, handled the tests. A male and female, one infected with syphilis, would be brought together in a cell and forced into sex with each other. It was made clear that anyone resisting would be shot.<ref name="gold-testimony"/>}}

After victims were infected, they were vivisected at different stages of infection, so that internal and external organs could be observed as the disease progressed. Testimony from multiple guards blames the female victims as being hosts of the diseases, even as they were forcibly infected. Genitals of female prisoners that were infected with syphilis were called "jam-filled buns" by guards.<ref name="gold-testimony"/>

Some children grew up inside the walls of Unit&nbsp;731, infected with syphilis. A Youth Corps member deployed to train at Unit&nbsp;731 recalled viewing a batch of subjects that would undergo syphilis testing: "one was a Chinese woman holding an infant, one was a [[White émigré#In China|White Russian]] woman with a daughter of four or five years of age, and the last was a White Russian woman with a boy of about six or seven."<ref name="gold-testimony"/> The children of these women were tested in ways similar to their parents, with specific emphasis on determining how longer infection periods affected the effectiveness of treatments.

==== Rape and forced pregnancy ====
Female prisoners were forced to become pregnant for use in experiments. The hypothetical possibility of [[vertical transmission]] (from mother to child) of diseases, particularly syphilis, was the stated reason for the torture. Fetal survival and damage to mother's reproductive organs were objects of interest. Though "a large number of babies were born in captivity", there have been no accounts of any survivors of Unit&nbsp;731, children included. It is suspected that the children of female prisoners were killed after birth or [[Abortion|aborted]].<ref name="gold-testimony"/>

While male prisoners were often used in single studies, so that the results of the experimentation on them would not be clouded by other variables, women were sometimes used in bacteriological or physiological experiments, sex experiments, and as the victims of [[sex crimes]]. The testimony of a unit member that served as a guard graphically demonstrated this reality:

{{blockquote|One of the former researchers I located told me that one day he had a human experiment scheduled, but there was still time to kill. So he and another unit member took the keys to the cells and opened one that housed a Chinese woman. One of the unit members raped her; the other member took the keys and opened another cell. There was a Chinese woman in there who had been used in a frostbite experiment. She had several fingers missing and her bones were black, with [[gangrene]] set in. He was about to rape her anyway, then he saw that her sex organ was festering, with [[pus]] oozing to the surface. He gave up the idea, left and locked the door, then later went on to his experimental work.<ref name="gold-testimony"/>}}