THE MOLECULAR FORCES IN PLANTS. 



221 



of the dish by means of cotton wool. The cork K' receives one 

 limb of the glass tube Gl, which is about 2 mm. in calibre. The 

 other limb of this tube runs alongside a millimetre scale. 



FIG. 85. Apparatus for measuring the absorption of water by transpiring plants. 



At the commencement of the experiment U and Gl are com- 

 pletely filled with water, the bottom of P is covered with chloride 

 of Calcium, and the bell-glass is put on. After a time we ascer- 

 tain the position of the meniscus in 01, and can now determine the 

 consumption of water by the plant by noting, say every five 

 minutes, how far the meniscus in Gl is carried back. To raise the 

 temperature of the air under by a few degrees C., it is only 



