CHLOROPHYLL AND GROWTH 



127 



nected with an aspirator, by which the air was 

 occasionally renewed. Several vessels con- 

 taining two to five grams of solid potassium 

 hydrate were placed inside of the bell-jar. 

 The potassium absorbed water rapidly and 

 soon dissolved. To provide against the dry- 

 ness of the inclosed air thus induced a large 

 sponge saturated with water was placed near 

 the plant. These precautions furnish normal 

 conditions except in the composition of the 

 air, from which almost all of the carbon diox- 

 ide is taken. It is of course understood that 

 the plant is constantly giving off this sub- 

 stance as a result of its oxidation processes, 

 and it may be imagined as forming a diffuse 

 stream from the plant to the vessels contain- 

 ing the potassium solutions. The amount ac- 

 tually present in the bell-jar at any time how- 

 ever must have been quite small. The potas- 

 sium solutions were renewed once each week. 

 Plants of Arissema grown in the apparatus 

 described above exhibited a normal develop- 

 ment during the opening of the bud, and the 

 preliminary stages of the unfolding of the 

 leaves, which are crumpled in the bud during 

 a period of two to four days. The develop- 

 ment process was- arrested, however, at a 

 very early stage, and the laminae were un- 

 folded only so far as to expose the ventral sur- 

 face, and the crumpled appearance was not 



Growih in the 

 absence of 

 carbon dioxide 



