224 Plant Physiology 



two or three folds of white cloth. Insert thermometers, and 

 equalize the temperatures as well as possible. At intervals 

 contrast the rate of starch accumulation in the two cases. 



Carbon dioxid and photosynthesis (starch accumulation). 

 In this experiment one plant (A) is exposed to a current of air 

 deprived of CO 2 , and a control (B) to similar conditions, except 

 that the air is natural. Arrange the experiment preferably in 

 the greenhouse or in the open, but a south window is also a pos- 

 sible situation. 



Place the plants (Fuchsia is desirable) in the dark over night 

 and keep them darkened until demanded. Each is covered by 

 a tubulated bell glass (and with (A) is included a dish of 10 per 

 cent potassium hydrate solution). Seal jar (A) to a ground 

 glass or metal base, and cover both with a 2-holed rubber stopper, 

 one hole serving for a connection with an aspirator or filter pump, 

 and the other (in A only) connected with potassium hydrate 

 wash bottles. When connections are tight, draw air through 

 (A) until a baryta- water wash bottle shows no further CO 2 in 

 the chamber. Then draw through both (A) and (.B) a current of 

 air for several hours, or as long as the experiment may be con- 

 tinued in the light, and test the leaves from each plant for starch. 



REFERENCES 



BLACKMAN, F. F., and MATTHEI, G. L. C. Experimental Re- 

 searches in Vegetable Assimilation and Respiration. Proc. 

 Roy. Soc. 76 B : 402-460, 1905. 



BROWN, H. T., and ESCOMBE, F. Static Diffusion of Gases and 

 Liquids in Relation to the Assimilation of Carbon [etc.]. 

 Phil. Trans. Roy. Soc. 193 B : 223-291, 1900. 



BROWN, H. T., and WILSON, W. E. On the Thermal Emissivity 

 of a Green Leaf in Still and Moving Air. Proc. Roy. Soc. 

 76 B : 122-137, 1905. 



BROWN, H. T., and ESCOMBE, F. Physiological Processes of 

 Green Leaves. Proc. Roy. Soc. 76 B : 29-111, 1905. 



CZAPEK, F. Die Ernahrungsphysiologie der Pflanzen seit 1896. 

 Progressus Rei Botanicse. 1 : 419-532 [468-477]. 



