440 MAMMALIAN RADIATION GENETICS 



11. Lea, D. E., Effects of radiation on germ cells: dominant lethals and hereditary 

 partial sterility, Brit. J. Radiol, Supplement 1: 120-137, 1947. 



12. Lorenz, E., W. E. Heston, A. B. Eschenbrenner, and M. K. Deringer, Biological 

 studies in the tolerance range. Radiology, 49 : 274-285, 1947. 



13. Otis, E. M., Intra-uterine death time in semi-sterile mice, Anat. Record, 105: 

 53, 1949. 



14. Snell, G. D., X-ray sterility in the male house mouse, J. Exptl. Zool., 65: 421-441, 

 1933. 



15. Snell, G. D., The induction by x-rays of hereditary changes in mice. Genetics, 

 20:545-567, 1935. 



16. Snell, G. D., The induction by irradiation with neutrons of hereditary changes 

 in mice, Proc. Natl. Acad. Sci., 25: 11-14, 1939. 



17. Snell, G. D., Linkage studies with induced translocations in mice. Genetics, 26: 

 169, 1941. 



18. Snell, G. D., An analysis of translocations in the mouse. Genetics, 31: 157-180, 

 1946. 



19. Snell, G. D., and P. C. Aebersold, The production of sterility in male mice by 

 irradiation with neutrons, Proc. Natl. Acad. Sci., 23: 374-378, 1937. 



20. Snell, G. D., and F. B. Ames, Hereditary changes in the descendants of female 

 mice exposed to roentgen rays. Am. J. Roentgenol. Radium Therapy, 41: 248-255, 

 1939. 



21. Spencer, W. P., and C. Stern, Experiments to test the validity of the linear 

 r-dose/mutation frequency relation in Drosophila at low dosage, Genetics, 33: 

 43-74, 1948. 



22. Wallace, B., Autosomal lethals in experimental populations of Drosophila mela- 

 nogaster. Evolution, 4: 172-174, 1950. 



23. Wright, S., Discussion on population genetics and radiation, /. Cellular Comp. 

 Physiol, 35: Supplement 1, 187-205, 1950. 



DISCUSSION 

 Muller: 



I should like to re-emphasize Russell's remarks on translocation effects, pro- 

 duced when mature sperm are radiated. If the sperm used in the fertility studies 

 are obtained after the sterile period, no translocation effects are seen. It is 

 evident that the translocation effects have disappeared because of death of the 

 involved sperm, and it should be re-emphasized that genie mutations almost 

 certainly exist but w^ere not capable of demonstration under the circumstances 

 of the experiments done to date. 



