1. Gilbert , Exp. Farms (Ottawa) Report, p. 300, 1904.
2. Kaupp , North Carolina Exp. Stat. Bull., 1915.
3. Ebikson , Missouri State Poultry Association Year Book (1924), and Biennial Report of the Missouri State Poultry Board for the Years 1923–1924, pp. 40–41.
4. Coste and Gerk , quoted from Busquat, La Fonction sexuelle, Paris, p. 127.
5. Hammond , Reproduction in the Rabbit, Oliver and Boyd, 1925.