Following C. W. Woodworth and William E. Castle, around 1908 Morgan started working on the fruit fly "Drosophila melanogaster", and encouraging students to do so as well. With Fernandus Payne, he mutated "Drosophila" through physical, chemical, and radiational means. He began cross-breeding experiments to find heritable mutations, but they had no significant success for two years. Castle had also had difficulty identifying mutations in "Drosophila", which were tiny. Finally in 1909, a series of heritable mutants appeared, some of which displayed Mendelian inheritance patterns; in 1910 Morgan noticed a white-eyed mutant male among the red-eyed wild types. When white-eyed flies were bred with a red-eyed female, their progeny were all red-eyed. A second generation cross produced white-eyed males—a sex-linked recessive trait, the gene for which Morgan named "white". Morgan also discovered a pink-eyed mutant that showed a different pattern of inheritance. In a paper published in "Science" in 1911, he concluded that (1) some traits were sex-linked, (2) the trait was probably carried on one of the sex chromosomes, and (3) other genes were probably carried on specific chromosomes as well.