212 LIFE: ITS NATURE AND ORIGIN 



tissues or organs contribute to the molecular melee in the organ- 

 ism units capable of determining their own specific type of cell." 

 The simple processes of circulation and diffusion may thus 

 help to lift from the genes and the chromosomes some of the tre- 

 mendous responsibilities placed upon them by considering them 

 as the sole carriers of heredity. The great numbers and varieties 

 of specific molecules trailing along in the gamete cytoplasms, and 

 especially numerous in the ovum, act through the catalyst 

 entelechy as cooperators with and supplementors of the genes. 



REFERENCES 



1 Presidential address before the Botanical Society of America (Science (1939) 

 89, 41-46), on "The Cell and the Problem of Organization." 



2 Am. Naturalist (1946) 80, 497-505. 



3 "Uber Entwicklungsgeschichte der Tiere," 1828. 



4 Brody, "Bioenergetics and Growth," p. 484, Reinhold Pub. Corp., 1944. 



5 "How we came by our bodies," New York, 1936. 



6 G. Pincus, Cold Spring Harbor Symposia on Quantitative Biology (1937) 5, 44. 

 The rabbit passes half (18 days) of its development before the fetus outweighs the 

 placenta. 



7 Cf. C. M. Child, "Individuality in organisms," University of Chicago Press, 1915. 

 In recent experiments, Child has demonstrated oxidation-reduction gradients in 

 developing embryos, by the use of suitable dyes, e.g., indophenol blue, Janus green, 

 in high nontoxic dilutions. The colors developed correspond to the local degree of 

 activity of an intracellular oxidizing enzyme, now believed to be cytochrome oxidase 

 (Proc. Nat. Acad. Sci. (1941) 27, 523-528; /. Exptl. Tool. (1945) 100, 577-589). 



8 Arch. Entw. Mech. (1933) 128, 584; (1934) 132, 225. 



9 C H. Waddington, Nature (1930) 125, 924; Phil. Trans. Roy. Soc. B. (London) 

 (1932) 221, 179. 

 9a "Biochemistry and Morphogenesis," Cambridge Univ. Press, 1942. 

 10 Arch. Entw. Mech. (1925) 106, 357. 

 ^Naturwiss. (1933) 21, 766; Arch. Entw. Mech. (1934) 132, 307. 



12 B. Mayer, Naturwiss. (1939) 27, 277. 



13 Arch. Entw. Mech. (1927) 111, 341. 



14 They obtained inductions with the following polyhydrocarbons and steroids 

 (structural formulas given by Needham, lib. cit., pp. 245-6): 



Estrogens: l:9-dimethylphenanthracene 



9:10-dihydroxy-9:10-di-n-butyl-9:10-dihydro-l:2:5:6-dibenzanthracene 



estrone (female sex hormone) 



4:4'-dihydroxy-diphenyl 



1:2 dihydroxy-l:2-di-a-naphthyl-acetnaphthene 



5:6-cyc/o-penteno-l :2 benzanthracene 

 Carcinogens: 3:4-benzpyrene 



methylcholanthrene 



styryl blue 



sodium l:2:5:6-dibenzanthracene-endo-a -^-succinate* 

 • Optimum dosage (yielding 40 per cent inductions where implant was retained) 

 was 0.0125 7 per embryo. (S. C. Shen, /. Exp. Biol. (1939) 16, 143). 

 i° Biol. Bull. (1934) 67, 244. 



