Shoot Histogenesis and the Subapical Meristem 577 



ACKNOWLEDGMENT 



The authors would like to acknowledge the excellent technical 

 assistance of Miss Joan Roach and Mr. Charles F. Bretz throughout 

 the course of this investigation and in the preparation of the paper. 

 We are indebted to Dr. F. W, Went for making the facilities of the 

 Earhart Plant Research Laboratory (California Institute of Technol- 

 ogy, Pasadena, California) available to us for the temperature studies. 

 Finally, we wish to thank the National Science Foundation and the 

 Merck, Sharp and Dohme Laboratories for financial support. 



LITERATURE CITED 



1. Bindloss, Elizabeth A. A developmental analysis of cell length as related to 

 stem length. Amer. Jour. Bot. 29; 178-188. 1942. 



2. Brian, P. W., and Hemming, H. G. The effect of maleic hydrazide on the 

 growth response of plants to gibberellic acid. Ann. Appl. Biol. 45: 489^97. 

 1957. 



3. Brown, R. The effects of temperature on the durations of the different stages 

 of cell division in the root tip. Jour. Exper. Bot. 2: 96-110. 1951. 



4. Bukovac, M. J., and Wittwer, S. H. Gibberellic acid and higher plants: I. 

 General growth responses. Quart. Bui. Mich. Agr. Exper. Sta. 39: 307-320. 

 1956. 



5. Cathey, H. M. Changing growth and flowering of mums. Florists Rev. 122: 

 25. 26, 30. April 24, 1958. 



6. • — . Mutual antagonism of growth control of Chrysanthemum morifolium 



by gibberellin and Amo-1618. Plant Physiol. 33 (suppl.): xliii. 1958. 



7. Crafts, A. S., Currier, H. B., and Drever, H. R. Some studies on the herbicidal 

 properties of maleic hydrazide. Hilgardia. 27: 723-757. 1958. 



8. Greulach, V. A., and Haesloop, J. G. Some effects of maleic hydrazide on inter- 

 node elongation, cell enlargement, and stem anatomy. Amer. Jour, Bot. 41: 

 44-50. 1954. 



9. Harting, M. G. Recherches micrometriques sur le developpement des parties 

 elementaires de la tige annuelle des plantes dicotyledonees. Ann. Sci. Nat. 

 Bot. III. 4: 210-279. 1845. 



10. Kato, J. Studies on the physiological effect of gibberellin. II. On the inter- 

 action of gibberellin with auxins and growth inhibitors. Physiol. Plant. II: 

 10-15. 1958. 



11. Lang, A. Stem elongation in a rosette plant, induced by gibberellic acid. Natur- 

 wis. 43: 257, 258. 1956. 



12. , Sachs, R. M., and Bretz, C. Effets morphogenetiques de la gibberelline. 



Bui. Soc. Fr. Physiol. Veget. 5: 1-19. 1959. 



13- , Sandoval, J. A., and Bedri, A. Induction of bolting and flowering in 



Hyoscyamus and Samolus by a gibberellin-like material from a seed plant. 

 Proc. Nat. Acad. Sci. U. S. 43: 960-964. 1957. 



14. Marth, P. C, Preston, W. H., and Mitchell, J. W. Growth-controlling effects 

 of some quaternary ammonium compounds on various species of plants. Bot. 

 Gaz. 115: 200-204. 1953. 



15. Phinney, B. O., West, C. A., Ritzel, M., and Neely, P. M. Evidence for "gibberel- 

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

 404. 1957. 



