500 B. O. Phinncy 



for bean factor II, etc. As yet there is no evidence to suggest such an 

 alternate explanation. 



The evidence presented in this paper suggests that the primary 

 action of the mutant genes c/^, dc,, d-^, dr^, and an^ is to control the 

 amount of native gibberellins in Zca mays by interfering with different 

 steps in a biochemical pathway leading to a gibberellin product nec- 

 essary for normal growth. The present evidence would suggest that 

 the gene d^ is controlling a terminal step in this series. The lower 

 auxin level found in certain dwarf mutants of Zea mays is attributed 

 to an indirect effect of the dwarfing genes. 



LITERATURE CITED 



1. Anderson, E., and Pettem, F. D. Dwarfs of Zea mays. Corn Co-op News Let- 

 ter. 30: 9, 10. 1956. 



2. , and Pettem, F. D. Dwarfs of Zea viays. Corn Co-op News Letter. 31: 



29, 1957. 



3. Emerson, R. A., Beadle, G. \V., and Eraser, A. C. A summary of linkage stud- 

 ies in maize. Cornell E\per. Sta. Mem. 180: 83 pp. 1935. 



4. Finsham, J. R. S. The role of chromosomal loci in enzyme formation. Proc. 

 10th Int. Cong. Genet. 1: 355-363. 1958. 



5. Harris, R. Auxin relations in a dicarf-l allele of 7.ea mays L. Ph.D. Thesis, 



Univ. Calif. Los Angeles. 



6 Horowitz, N. H. Biochemical genetics of Neurospnra. Ad\. Genet. 3: 33-71. 

 1950. 



7. Neely, P. M. The development and use of a bioassay for gibberellins. I'liD. 

 Thesis, Univ. Calif. Los Angeles. 1959. 



8. , and Phinney, B. O. The use of the mutant dicorj-l of maize as a 



quantitative bioassay for gibberellin activity. Plant Physiol. 32 (sujjpl.): xxxi. 

 1957. 



9 Piiinney, B. O. Growth response of single-gene dwarf mutants in maize to 

 gibberellic acid. Proc. Natl. Acad. Sci. U. S. 42: 185-189. 1956. 



10. , and West, C. A. The growth response of single gene dwarf nuitants 



of Z,ca mays to gibberellins and to gibbcrellin-likc substances. Proc. Int. 

 Genet. Symp. pp. 384, 385. 1957. 



11. , West, C. A., and Neely, P. M. Single gene dwarf mutants of Zea mays 



and their dilfcrcntial growth response to gibberellins and to gibberellin-likc 

 substances. C^orn Co-op News Letter. 32: 6, 7. 1958. 



12. , West, C. A., and Neely, P. M. Biological properties ot the gibberellin, 



bean factor II. (In preparation.) 



13. , West, C. A., Ritzel, M., and Neely, P. M. Evidence for "gibberellin- 



like" substances from flowering plants. Proc. Natl. Acad. Sci. U. S. 43: 398- 

 404. 1957. 



14. van Overbeek, J. The growth hormone and the dwarf ivpe ot growth in lorn. 

 Proc. Natl. Acad. Sci. U. S. 21: 292-299. 1935. 



15. . Auxin production in seedlings of dwarf mai/c. Plant Plivsiol. 13: ,">87- 



598. 1938. 



