No. 1, August, 1921] PHYSIOLOGY 79 



leaves, and of flower stalks; the evolution of CO2 in alcoholic fermentation; and water absorp- 

 tion by plants. There is a discussion of the formula of autocatalysis presented by Robertson, 



log — ^ = Kit- ti), 

 A- X 



where X = quantity of substance formed at timet, A = final (limiting) value of x, K is sl con- 

 stant of the reaction, and ti is the time at which x = — . Also, there is consideration of the 



formula presented by Mitscherlich, 



/n n — \ n — 



— C. X, 



where y = amoimt of substance formed at stage x, A = final (limiting) value of y, and n = num- 

 ber of stages. The author concludes that Robertson's formula gives more nearly correct 

 representation of physiological processes than that of Mitscherlich. He discusses sources of 

 error of determinations and necessary precautions. The original should be consulted. — 

 H. S. Reed. 



MOVEMENTS OF GROWTH AND TURGOR CHANGES 



520. Anonymous. [Rev. of: Loeb, Jaques. Forced movements, tropisms, and animal 

 conduct. 209 p., 42 fig. J. B, Lippincott & Co.: London and Philadelphia, 1918.] Sci. Prog. 

 [London] 14: 1G7-168. 1919. 



521. Fyson, p. F., and K. Venkataraman. Note on curvature of cut stems of Bryophyllum 

 calycinum. Jour. Indian Bot. 1: 337-343. PI. 2. 1920. — This paper is inspired by J. Loeb 

 and is an answer to various papers by him on growth in Bryophyllum calycinum. [See Bot. 

 Absts. 1, Entries 68, 273, 736; 2, Entries 181, 858, 859.] The authors conclude from experi- 

 ments conducted in Madras on this plant: That curvature of horizontally supported stems 

 is due to the weight of the stem, and not to the formation of geotropic hormones by any leaves 

 that may remain attached; that root formation by stems bears no apparent relation to the 

 presence or absence of leaves; that the formation of roots from the notches of leaves depends 

 on moisture supply, and not on leaf position; that "neither the stem itself, not the opposite 

 bud, nor the axillary bud, exert anj' absolute inhibition on the development of the marginal 

 notches, and probably affect it very little"; that root pressure or a developing terminal bud 

 exert no influence on the formation of roots from the notches of attached leaves; and finally 

 that "our observations confirm those of Klebs on the eff'ect of an excess of water on adventi- 

 tious root formation." — Winfield Dudgeon. 



522. Phillips, Thomas G. Chemical and physical changes during geotropic response. Bot. 

 Gaz. 69: 168-178. 1920. — Definite moisture changes accompany geotropic bending in corn 

 nodes. During the early stages of bending there is a greater percentage of moisture in the 

 concave flank. When the process has developed, the percentage of water is greater in the 

 convex flank. Although the titratable acidity is greater in the convex flank, the diff'erences 

 are very slight. The results on hydrogen-ion concentration, although uniform in direction, 

 are not numerous enough to serve as a basis for conclusions. It is impossible, with the data 

 obtained, to correlate the geotropic bending of etiolated Vicia Faha shoots with differences 

 in moisture, titratable acidity, hydrogen-ion concentration, catalase activity, or the distri- 

 bution of sugars and nitrogen-containing substances. — Thomas G. Phillips. 



523. RicoME, H. L'orientation des rameaux dans I'espace. [The orientation of stems.] 

 Compt. Rend. Acad. Sci. Paris 171 : 734-735. 1920. — This is an addition to a recent article in 

 an earlier number of the same volume in which the author attributes the weight which influ- 

 ences negatve geotropism to the distribution of water in the plant. [See also Bot. Absts. 

 8, Entry 663.]— C. //. Farr. 



