30 ASSIMILATION. [CH. II 



smeared with wax-mixture, and the junction with the 

 glass plate is made secure by a little embankment of 



FIG. 8. Exp. 35. 



wax-mixture melted into the angle with a hot wire. The 

 aperture of the bell is closed by a rubber cork pierced for 

 the tube T, which contains soda-lime. 



The apparatus should be placed out of doors or in a 

 brightly lighted greenhouse. A control-plant must be 

 fitted up in a similar way except that G may be dispensed 

 with and that T must be filled with sawdust or some 

 indifferent coarsely grained powder. Or G may contain 

 H 2 SO 4 lest the air in the first jar should be drier than 

 in the control. 



