that was the basis of the Nobel Prize. Lenhoff noted there is evidence that Spemann may have known about Ethel Browne Harvey's work as well, as she had sent a copy of her paper to Spemann, and someone had underlined the portion of the paper that discussed the significance of her work. 1926 In 1926, no prize was awarded because the works of the two nominees Johannes Andreas Grib Fibiger and Katsusaburo Yamagiwa were considered undeserving. Fibiger had demonstrated that he could induce stomach cancer in rats using a roundworm Gongylonema neoplasticum that he discovered (but which he preferred to call Spiroptera carcinoma). Yamagiwa followed suit and induced cancer in rabbit by applying coal tar on the rabbit's ears. Theirs were the first experimental induction of cancer. One of the assessors Hilding Bergstrand concluded that "one cannot, at this point, find much support for the possibility that the work of Fibiger and Yamagiwa will have great importance in the solving of the riddle of cancer. Under such circumstances I do not consider these discoveries worthy of the Nobel Prize." In 1927, Fibiger was again nominated alongside Otto Heinrich Warburg and Julius Wagner-Jauregg; but Yamagiwa was excluded. The Nobel Committee decided to award the 1926 prize jointly to Fibiger and Warburg, and the 1927 prize to Wagner-Jauregg. But at the final selection, Karolinska Institute rejected Warburg. The 1926 prize went solely to Fibiger "for his discovery of the Spiroptera carcinoma". Fibiger's "finding" was discredited by other scientists shortly thereafter. Particularly after the last major experiment in 1952, it was established that the roundworm is not carcinogenic, and that cancers developed in Fibiger's experiments were due to vitamin A deficiency. Yamagiwa's exclusion was also criticised, because his experiment was a valid finding. Coal tar (and substances containing polycyclic aromatic hydrocarbons, or PAHs) are now known to be true carcinogens. Yamagiwa's work has become the primary basis for this line of research. Encyclopædia Britannica guide to Nobel Prizes in cancer research mentions Yamagiwa's work as a milestone without mentioning Fibiger. 1923 The 1923 prize was awarded to Frederick Banting and John Macleod "for the discovery of insulin". Banting clearly deserved the prize, but the choice of Macleod as co-winner was controversial. Banting felt that Charles Best was the proper corecipient, while Macleod had merely given them laboratory space at the University of Toronto while Macleod was away for the summer. On his return,