Charles Claude Guthrie, an American physiologist, made significant contributions in his field and even collaborated with Alexis Carrel, a French physician who won the Nobel Prize in Physiology for Medicine in 1912 for their work on vascular surgery.
Guthrie, although he should have been included, was denied the prize probably due to his head transplant experiments where he would sew the head of one dog onto another.
Surprisingly, his experiments actually showed some success with the severed heads being kept artificially alive during the transplant.
