Vegetable Assimilation and Respiration. 327 



Part III. Comparison of Assimilation Mates in Solutions of Sodium Bicar- 

 bonates and of Carbonic Acid. — By the aid of the "bubblers" described in 

 Part I these rates are carefully compared for solutions of known strength. It 

 is shown that a solution of a bicarbonate gives just about that rate of 

 bubbling which corresponds to the CO2 concentration expected to arise in it 

 by spontaneous decomposition. Solutions of bicarbonates, when very dilute, 

 give initial CO2 diffusion effects, conform to Blackman's laws of interaction 

 of limiting factors, and generally behave as solutions of carbonic acid. 

 Angelstein's view that plants have the power of splitting bicarbonates actively 

 is erroneous. 



In conclusion I wish to express my thanks to Dr. Blackman, both for 

 advice during the course of the experiments and for help in preparing this 

 paper when stress of ofl&cial duties, preventing me from giving the necessary 

 attention to it, had resulted in an indefinite postponement of publication. 



LITERATURE. 



Angelstein, U., 191 1. " Uber die Kohlensaiureassimilation submerser Wa'sserpflanzen in 

 Bikarbonat- und Karbonatlosungen," ' Beitrage zur Biologic der Pflanzen,' vol. 10, 

 pp. 87-117. 



Blackman, F. F., and Smith, A. M., 1911. " On Assimilation in Submerged Water 



Plants, and its relation to the Concentration of Carbon Dioxide and other Factors, 



' Roy. Soc. Proc.,' B, vol. 83, pp. 389-412. 

 Darwin, Fr., and Pertz, D. F. M., 1896. " On the EflFect of Water Currents on the 



Assimilation of Aquatic Plants," ' Proc. Camb. Phil. Soc.,' vol. 9, p. 76. 

 Jacobi, B., 1899. "Ueber den Einfluss verschiedener Substanzen auf die Athmung 



und Assimilation submerser Pflanzen," ' Flora,' vol. 76, pp. 289-327. 

 Kniep, H., 1915. " Uber den Gasaustausch der Wasserpflanzen : ein Beitrag zur Kritik 



der Blasenzahlmethode," ' Jahrb. f. Wiss. Bot.,' vol. 56, pp. 460-510. 

 PantanelH, E., 1904. " Abhangigkeit der Sauerstoffausscheidung belichteter Pflanzen 



von ausseren Bedingungen," ' Jahrb. f . Wiss. Bot.,' vol. 39, pp. 167-228. 

 Treboux, 0., 1903. " Einige stofiliche Einflusse auf die Kohlensaureasaimilation bei 



submersen Pflanzen," ' Flora,' vol. 92, pp. 49-76. 

 Willstatter, W., and Stoll, A., 1918. ' Untersuchungen iiber die Assimilation der 



Kohlensaure,' Berlin. 



VOL. XCII. — B. 



