112 pringsheim's researches on chlorophyll. 



h '.3 been niisinterpreted. Fanniitzin/ for example, took 

 this as proof of the diminution in amount of destruction of 

 carbonic acid in sunlight, and of its beino; less than in 

 bright diffuse daylight. But it is niore rationally explained 

 by an increased combustion in direct sunlight, so that the 

 assimilation and respiration curves approach. 



Tissues which are not green, and plants, such as phanero- 

 gamous saprophytes and Fungi, as they want the elements, 

 especially the easily oxidised assimilation-products of the 

 chlorophyll-corpuscles, which, in green cells, so readily 

 absorb oxygen in light, are not so sensitive to light. A 

 marked increase of carbonic acid accumulation does not 

 take place in them, even in diffuse daylight of low intensity. 

 Some researches in this direction by Drude^ on Monotropa, 

 and by Wolkoff and Mayer^ upon germinating plants, have 

 shown an increase in respiration in light. The latter found 

 the differences very small, and considered them as tending 

 to show that light had no important influence on respira- 

 tion. But their results may be taken as supporting the 

 theory here set forth. In experiments on respiration ger- 

 minating seeds and green organs cannot be fairly compared 

 as regards the subs-tances used up. In the former it is the 

 reserve materials — starch, fat, &c. — which, after metastatic 

 change, are oxidised, whilst in the active green cells these 

 substances, as has been shown, take no share in the respira- 

 tion, but it is the primary assimilation-products or their 

 immediate derivates which undergo combustion. If, there- 

 fore, with such unfavourable objects, an increase in the car- 

 bonic acid formation is observed, it is the more a distinct 

 indication of the influence of light on respiration. 



^ " Melanges biologiques," ' Bull. d. I'Acad. Imper. d. St. Petersbourg,' 

 torn. X, 1880. 



- ' Biologic der Monotropa Hipopitys,' Gotlingen, 1873. 

 ^ ' Laudwirthschat'tliche Jahrbiiclier,' 1874. 



(To be continued.) 



