Ta kuma iya nuna cewa, a wasu shuke-shuke, spontaneous chromosome karya ya faru a cikin Kwayoyin endosperm. A lokacin da mitosis, ta lura da cewa iyakar karya chromatids aka koma bayan da chromosome maimaitawa. A wani lokaci na mitaphosis, da karya chromosomes kafa wani chromatid gada, wanda aka karya a lokacin da chromatids koma zuwa ga cell sandunan. A lokacin da ta lokaci a Missouri, McClintock fadada ta bincike a kan sakamako na X-haskoki a kan mai zuwa mitosis, da kuma sake zagayowar da aka jawo, haddasa m maye gurbi, wanda zai iya bambanta a matsayin ta iya ganewa a cikin chromosome karyewa a cikin irradiated masara Kwayoyin. McClintock kuma ya iya nuna cewa, a wasu shuke-shuke, spontaneous chromosome karya ya faru a cikin Kwayoyin endosperm. A lokacin da mitosis, ta lura da cewa iyakar karya chromatids aka koma bayan chromosome maimaitawa. A wani wuri a Missouri, da farko na yi imani da cewa babu wani abu da zai iya bayyana a nan,
Cibiyar Carnegie ta Washington