30 



ASSIMILATION. 



[CH. II 



smeared with wax-mixture, and the junction w^ith 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. We find that ex- 

 posure from 10 a.m. until the afternoon of the next day 

 gives good results. 



