384 Quantitative Analysis of the Growth o/Helianthus annuus. 



decreases with the age of the organ. The initial respiratory index of 

 successive leaves — i.e., the respiratory index of the stem-apex — decreases 

 with the age of the plant, indicating that the respiratory index of the 

 meristematic tissue decreases with age. The fall in the respiratory index of 

 the meristematic tissue and young leaves shows that the fall in the 

 respiratory index of the whole plant is not, as might be expected, due 

 entirely to the increase in proportion of such tissues as mechanical and 

 water-conducting tissue. 



The fall in the value of the respiratory index with age follows closely that 

 in the value of the relative growth rate, thus indicating a close connection 

 between the " internal " factor for respiration and the " internal " factor for 

 growth. 



In conclusion, the authors wish to express their thanks to Mr. P, Parija and 

 Mr. E. J. Maskell for carrying out titrations, and to Dr. F. F. Blaelcman, F.E.S., 

 for ever ready advice and stimulating criticism. 



The expenses of this investigation were partly defrayed by a grant from 

 the Dixon Fund of the University of London. 



LITERATURE CITED. 



(1) Briggs, G. E., Kidd, E., and West, C, " A Quantitative Analysis of Plant Growth. 



Part T," ' Ann. Appl. Biol.,' vol. 7, p. 103 (1920). 



(2) Gore, H. C, "Studies in Fruit Respiration," 'U.S. Dept. Agric. Bur. of Chem., 



Bull. 142,' 1911. 



(3) Hornberger, R., " Chemische Untersuchungen liber das Wachstum der Maispflanze 



unter Mitwirkung von von Raumer," 'Landw. Jahrb.,' vol. 11, p. 378 (1882). 



(4) Kidd, F. West, G, and Briggs, G. E., " What is the Significance of the Efficiency 



Index of Plant Growth ?" 'New Phyt.,' vol. 19, p. 88 (1920). 



(5) Kuyper, J., "The Influence of Temperature on the Respiration of the Higher 



Plants," 'K. Akad. van Wetenschappen Amsterdam, Proc. Sect. Sci.,' vol. 12, 

 p. 219 (1910). 



(6) Nicolas, G., " Contributions a I'Etude des "Variations de la Respiration des Vegetaux 



avec rAge," ' Rev. G6n. de Bot.,' vol. 30, p. 209 (1918). 



(7) Palladin, V. I., " Recherches sur la Correlation entre la Respiration des Plantes et 



les Substances Azot6es actives," ' Rev. Gen. de Bot.,' vol. 8, p. 225 (1896). 



(8) West, C, Briggs, G. E., and Kidd, F., " Methods and Significant Relations in the 



Quantitative Analysis of Plant Grov^th," 'New Phyt.,' vol. 19, p. 200 (1920). 



