ve 
xu, c,1 Brown and Heise: Carbon Dioxide Assimilation 7 
on the assimilation, while the apparent effect of time is most 
marked in the latter experiments, which were with temperatures 
above 25° and where there is a decline in the rate of assimilation. 
THE WORK OF PRJANISCHNIKOW ON TYPHA 
The observation of Prjanischnikow * that the rate of assimila- 
tion in Typha latifolia in direct sunlight did not change with 
temperatures between 9.5° and 39° C. is in harmony with the 
results of the experiments previously mentioned. In diffused 
light he found a change in rate at different temperatures. The 
figures are not given in the review. The results from the ex- 
periments in direct sunlight indicate a temperature coefficient of 
about 1.0. 
THE WORK OF LUBIMENKOW 
Lubimenkow “ has determined the carbon dioxide assimilation 
of five conifers and three deciduous trees at varying angles to 
direct sunlight and at temperatures of 20°, 25°, 30°, 35°, 38° C. 
No details concerning his method are given in the article quoted, 
but there are enough discrepancies in individual series to indicate 
that the experimental error was great. The average temperature 
coefficient calculated for the twenty-eight experiments for the 
interval 20°-30° C. was 1.4; for 25°-35° C. it was much lower. 
THE WORK OF MATTHAEI ON CHERRY LAUREL 
Matthaei ** made an extensive study of the relation of temper- 
ature to carbon dioxide assimilation in the leaves of cherry 
laurel, Prunus laurocerasus, garden variety rotundifolia; and 
reached the conclusion that if sufficient light and carbon dioxide 
were present the assimilation increased rapidly with increas- 
ing temperature between the limits —6° C. and +37° C. In 
a subsequent paper Blackman ** calculated that the ratio of in- 
crease in assimilation as expressed in Matthaei’s curve for the 
10° rise in temperature between 9° and 19° is 2.1. The state- 
ments that the van’t Hoff principle applies to photosynthesis are 
* Reviewed by Batalin in Bot. Jahresbericht 4 (1876) 897; see also 
Famintzin, A., in Ann. Sei. Nat. Bot. VI 10 (1880) 67-80. 
* Lubimenkow, W., Variations de l’assimilation chlorophyllienne avec 
la lumiére et la temperature, Compt. Rend. Acad. Sci. 143 (1906) 609. 
- * Matthaei, G. L. C., Experimental researches on vegetable assimilation 
and respiration. III. On the effect of temperature on carbon-dioxide 
assimilation, Phil. Trans. Roy. Soc. London B 197 (1905) 47-105. 
* Blackman, F. F., Optima and limiting factors, Ann. Bot. 19 (1905) 
281-295. 
