LIFE CYCLE OF HYDATINA SENTA 317 
Suuut, A. F. 1910 Studies in the life cycle of Hydatina senta. 1. Artificial 
control of the transition from the parthenogenetic to the sexual method 
of reproduction. Jour. Exp. Zool., vol. 8, no. 3, June, pp. 311-354. 
1911 a wu. The rdle of temperature, of the chemical composition of 
the medium, and of internal factors upon the ratio of parthenogenetic 
to sexual forms. Ibid., vol. 10, no. 2, February, pp. 117-166. 
1911 b The effect of the chemical composition of the medium on the 
life cycle of Hydatina senta. Biochem. Bull., vol. 1, no. 2, December, 
pp. 111-136. 
Suut, G. H. 1908 The composition of a field of maize. Amer. Breed. Assn., 
vol. 4. 
Wuitney, D. D. 1907 Determination of sex in Hydatina senta. Jour. Exp. 
Zool., vol. 5, no. 1, November, pp. 1-26. 
1909 Observations on the maturation stages of the parthenogenetic 
and sexual eggs of Hydatina senta. Ilbid., vol. 6, no. 1, pp. 137-146. 
Wotrtereck, R. 1909 Weitere experimentelle Untersuchungen iiber Artver- 
anderung, speziell ttber das Wesen quantitativer Artunterschiede bei 
Daphniden. Verh. d. deutsch. zool. Gesell., pp. 110-172. 
1911 Uber Veridnderung der Sexualitit bei Daphniden. Experimen- 
telle Untersuchungen tiber die Ursachen der Geschlechtsbestimmung, 
Internat. Rev. d. ges. Hydrobiol. u. Hydrogr., Bd. 4, Heft 1 and 2. 
April and June, pp. 91-128. 
