178 LIFE: ITS NATURE AND ORIGIN 



11 C. Auerbach, J. M. Robson, and J. G. Carr, Science (1947), 105, 243-247. 



12 The following also act as chemical mutagens; (CH 2 .CH 2 .S.CH2.CH 2 C1) 2 0; 

 (CH 2 .CH 2 C1) 3 N; CH S .N(CH 2 .CH 2 C1) 2 . The last two compounds are known as 

 "nitrogen mustards," and represent a class of compounds being used in cancer 

 research. 



13 "Action of Radiations on Living Cells," Cambridge University Press, 1946. 



14 "Environmental Transformation of Bacteria," Science (1934), 79, 466-470. 



15 Scientific Monthly (1926), 22, 185-192. 



16 "The Cell and Protoplasm," Pub. No. 14, Am. Assn. Adv. Science, 1940, pp. 44-55. 



17 Biol. Bull. (1915), 32, 249. 



18 /. Acad. Nat. Sci. Phila. (1902), 12, 1. 

 19 /. Exptl. Zool. (1935), 71, 209. 



20 Arch. Protozool. (1921) 43, 1; (1934), 83, 134. 



21 See J. Alexander, Scientia, October, 1933. 



22 "Hormones and Heredity," 1920. 



