IN THE DIVIDING ROOT-TIP CELLS OF THE ONION. 47 



(3) From the Qio values derived from these comparisons it is found 

 that each mitotic stage presents characteristic velocity-reactions to 

 temperature-increments. These reaction-values approximate van't 

 Hoff's expectations, thus indicating that most probably the repertoire 

 of activities constituting each such mitotic stage is composed of the 

 actions and interactions of those much more elementary physical and 

 chemical forces which measured in more isolated relations have been 

 shown to react in this same velocity-fashion. 



REFERENCES. 



Bayliss, W. M. Nature of enzyme action. London. 1911 



. The mechanism of chemical change in living organisms. Nature 97, 352-353. 



1916. 

 Chamberlain, C. J. Periodicity in mitosis. Bot. Gaz. 61, 242-243. 1916. 

 Child, M. C. Individuality in organisms. Chicago. 1915. 

 CoNKLiN, E. G. Cell size and nuclear size. Jour. Exp. Evol. XII. 1912. 

 . Experimental studies on nuclear and cell division. Jour. Acad. Nat. Sci. Phila. 



1912. 



. Why polar bodies do not develop. Proc. Nat. Acad. Sci. 1, 491-496. 1915. 



. Effects of centrifugal force on the polarity of the eggs of Crepidula. Proc. Nat. 



Acad. Sci. 2, 87-90. 1916. 

 Davenport, C. B. Action of heat upon protoplasm. Experimental Morphology, Ch. 



VIII, 219-273. 



. On normal growth. Experimental Morphology, Ch. x, 281-292. 



. Effects of heat on growth. Experimental Morphology, Ch. xviii, 450-469. 



. On scientific and plotting data and the frequency polygon. Statistical Methods, 



Ch. II, 10-18. 

 Green, J. Anatomy of plants. History of Botany (Sachs), 181-182. 1909. 

 Harvey, E. Newton. Effects of different temperatures on the medusa Cassiopea, with 



special reference to the rate of conduction of the nerve impulse. Carnegie Inst. 



Wash. Pub. No. 132. 1910. 

 Heidenhain, M. Die vitale Granulafarbung. Plasma und Zelle, 1, 434-472. 

 Kanitz, a. Temperatur und Lebensvorgange. Berlin. 1915. 

 Karsten, G. tjber Embryonales Wachstum und seine Tagesperiode. Zeit Bot., 7, 1-34. 



1915. 

 Kellicott, W. E. The daily periodicity of cell division and elongation in the root of 



Allium. Bui. Torr. Club., 31, 529-550. 1904. 

 Krough, August. On the influence of temperature on the rate of embryonic development. 



Zeit. f. All. Physiologie, 16, 163-177; Ibid., 16, 178-190. 

 Laughlin, Harry H. The dynamics of cell-di vision. Proc. Soc. Exp. Med. and Biol., 



XV, 8, No. 179 (1357), pp. 117-122. May 1918. 

 Lehenbauer, p. a. Growth of maize seedUngs in relation to temperature. Physiol. Res., 



5, 247-288. 1914. 

 Levi, G. II ritino e le modaUita della mitosi neUe cellue viventi coltivate in vitro. Arch. 



Ital. di. Anat. e di. Embr., 15, 243-264. 1916. 

 Lewis, W. H., and Margaret, R. The duration of the various phases of mitosis in the 



mesenchyme cells of tissue cultures. Anat. Rec, 13, No. 6, 359-367. 1917. 

 LiLLiE, Ralph S. Mass action in the activation of unfertilized starfish eggs by butyric 



acid. Journ. Biol. Chem., 24, 233-247. 1916. 

 . Physiology of cell division, vi. Rhythmical changes in the resistance of the 



dividing sea-urchin egg to hypotonic sea water, and their significance. Journ. 



Exp. Zool., 21, 369-402. 



