1. Bennett, C W. 1927. Mich State Coll Agric Exp Sta, Bot Sect Tech Bull No. 80.
2. Crainger, J. 1936. Nature 137, 31.
3. Ephrussi, B, and Beadle, G W. 1936. Am Nat 70, 218–225.
4. Harrison, A L. 1935. NY State Agr Exp Sta Tech Bull No. 236.
5. Huettner, A F. 1924. J Morph 249–265.