Experimental researches on vegetable assimilation and respiration.—XX. The energetic efficiency of photosynthesis in green plants: Some new data and a discussion of the problems

Abstract

The structural complexity of several photosynthesizing tissues is discussed. Equations are given for the absorption and transmission of light by Monostroma thallus. Measurements of photosynthesis were made on Phaseolus vulgaris, yellow elm, green elm, and Sambucus nigra. Yellow-red, green, or blue light was obtained from a 1500 watt lamp by means of gelatin filters. Incident energy was measured with a thermopile. The efficiency of photosynthesis was found to decrease from the red to the blue end of the spectrum. The results are discussed in relation to those of Ursprung, Reinke, Brown and Escombe, Wurmser, and Warburg and Negelein. The possible significance of the yellow pigments is discussed, and the efficiency of photosynthesis is considered from the point of view of photochemical theory.