SEX-DETERMINATION IN ASPLANCHNA 255 



Shull, a. F. 1910 Studies in the life cycle of Hydatina senta. I. Artificial 

 control of the transition from the parthenogenetic to the sexual 

 method of reproduction. Jour. Exp. ZooL, vol. 8, no. 3, pp. 311-354. 



1911 a II. The role of temperature, of the chemical composition of 

 the medium, and of internal factors upon the ratio of parthenogenetic 

 to sexual forms. Jour. Exp. ZooL, vol. 10, no. 2, pp. 117-166. 



1911 b Artificial production of the parthenogenetic and sexual phases 

 of the life cycle of H. senta. Amer. Nat., vol. 44, pp. 146-50. 



1912 III. Internal factors influencing the proportion of male pro- 

 ducers. Jour. Exp. ZooL, vol. 12, no. 2, pp. 283-317. 



Whitney, D. D. 1907 Determination of sex in Hydatina senta. Jour. Exp- 

 ZooL, vol. 5, no. 1, pp. 1-26. 



1910 Influence of external conditions upon the life cycle of Hydatina 

 senta. Science, N. S., vol. 32, pp. 345-49. 



1912 a Reinvigoration produced by cross-fertilization in Hydatina 

 senta. Jour. Exp. ZooL, vol. 12, no. 3, pp. 337-361. 



1912 b "Strains" in Hydatina senta. Biological Bulletin, vol. 22, no. 

 4, pp. 205-219. 



WoLTERECK, R. 1909 Weitere experimentelle Untersuchungen iiber Artveran- 

 derung, speziell iiber das wesen quantitativer Artunterschiede bei 

 Daphniden. Verb. d. deutsch. ZooL Gesell, pp. 110-172. 



