Passage: During her time at Missouri, McClintock expanded her research on the effect of X-rays on maize cytogenetics. McClintock observed the breakage and fusion of chromosomes in irradiated maize cells. She was also able to show that, in some plants, spontaneous chromosome breakage occurred in the cells of the endosperm. Over the course of mitosis, she observed that the ends of broken chromatids were rejoined after the chromosome replication. In the anaphase of mitosis, the broken chromosomes formed a chromatid bridge, which was broken when the chromatids moved towards the cell poles. The broken ends were rejoined in the interphase of the next mitosis, and the cycle was repeated, causing massive mutation, which she could detect as variegation in the endosperm. This breakage–rejoining–bridge cycle was a key cytogenetic discovery for several reasons. First, it showed that the rejoining of chromosomes was not a random event, and second, it demonstrated a source of large-scale mutation. For this reason, it remains an area of interest in cancer research today.Although her research was progressing at Missouri, McClintock was not satisfied with her position at the University. She recalled being excluded from faculty meetings, and was not made aware of positions available at other institutions. In 1940, she wrote to Charles Burnham, "I have decided that I must look for another job. As far as I can make out, there is nothing more for me here. I am an assistant professor at $3,000 and I feel sure that that is the limit for me." Initially, McClintock's position was created especially for her by Stadler, and might have depended on his presence at the university. McClintock believed she would not gain tenure at Missouri, even though according to some accounts, she knew she would be offered a promotion from Missouri in the spring of 1942. Recent evidence reveals that McClintock more likely decided to leave Missouri because she had lost trust in her employer and in the University administration, after discovering that her job would...

Question: What institution was she offered a position at?
Carnegie Institution of Washington