122 Quantitative Analysis of Plant Growth 



The incidence of the maxima is controlled by environmental condi- 

 tions — not by the environmental conditions operating at the time, but 

 by those obtaining at some previous stage in the life-history of the 

 plant. 



The fact that the curve for leaf-area per unit dry-weight throughout 

 the season (which has been calculated) shows a correspondence with 

 the growth-rate curve indicates that the physiological basis for increased 

 and decreased relative rate of growth is a corresponding change in the 

 assimilating area per unit dry- weight. This point will be dealt with in 

 the next chapter. 



Evidence from the quantitative analysis of plant growth for maize 

 indicates that the seedling leaves do not perform their normal assimila- 

 tory function till some time after their appearance. 



(To be continued.) 



LITERATURE CITED. 



(1) Blackman, V. H. The Compound Interest Law and Plant Growth. Ann. Bot. 



xxxm, 1919, p. 353. 



(2) Briggs, G. E. The Development of Photosynthetic Activity during Germination. 



Proc. Roy. Soc. (Lond.), B, xci, 1920, p. 249. 



(3) Burd, J. S. Rate of Absorption of Soil Constituents at Successive Stages of 



Plant Growth. Journ. Agric. Research, xviii, 2, 1919, p. 51. 



(4) Deleano, N. Etude sur le Role et la Fonction des Sels Mineraux clans la Vie de 



la Plante, Geneva, 1907. 



(5) Garreau. De la Respiration chez les Plantes (1). Ann. Sci. Nat. (Bot.), 3 e Ser., 



t. xv, 1851, p. 5. 

 (G) Hornberger, R. Untersuchungen iiber Gehalt und Zunahme von Sinapis alba 

 an Trockensubstanz und chemischen Bestandtheilen in 7-tagigen Vege- 

 tationsperioden. Landw. Versuchs-Stat. xxxi, 1S85, p. 415. 



(7) Irving, A. A. The Beginning of Photosynthesis and the Development of 



Chlorophyll. Ann. Bot. xxiv, 1910, p. 805. 



(8) Jones. W. J. and Huston, H. A. Composition of Maize at Various Stages of 



its Growth. Purdue Univ. Agric. Exp. Sta. Bull. 175, xvn, 1914. 



(9) Kidd, P. and West, C. Physiological Pre-Determination. IV. Review of 



Literature, Chapter III. Ann. Appl. Biol, v, 1919, p. 220. 



(10) Kreusler, U., Prehn, A. and Becker, G. Beobachtungen iiber das Wachs- 



thum der Maispflanze. Ixindw. Jahrb. vr, 1877, p. 759. 



(11) Landw. Jahrb. vi, 1877, p. 787. 



(12) Kreusler, U., Prehn, A. and Hornberger, R. Beobachtungen iiber das 



Wachsthum der Maispflanze. Landw. Jahrb. vir, 1878, p. 536. 



(13) Landw. Jahrb. vin, 1879, p. 617. 



