American anatomist Ivan Wallin (${}1883$–${}1969$) furthered the endosymbiotic hypothesis by experimentally testing the similarities between mitochondria, chloroplasts, and bacteria in the ${}1920$s. He published several papers supporting the hypothesis, including a ${}1926$ co-authored work with Konstantin Mereschkowski. Wallin claimed to culture mitochondria outside their host cells, but scientists dismissed this as bacterial contamination. Modern genome sequencing supports his critics, revealing that much of the mitochondrial genome transferred to the host cell's nucleus, preventing independent mitochondrial life.