Morris made some experimenting with grafting of ovaries in rabbits. In his notes he recorded a frequent trouble in the effort to make one set of rabbits immune to blood serum of another set of rabbits. The main issue was that tissue of any sort taken from one individual and planted in another is physiologically a stranger. The subject of gland grafting engaged his interest in the Nineties. He also noticed that ovarian grafting was so much more frequently possible than testis grafting, first of all because of the number of women donors, which he reported were much more ready than men to sacrifice a solid organ.