ON THE RESPIRATORY FUNCTION OF STOMATA. 25 



The baryta solution employed is of such a strength as 

 to unite with just half its volume of C0 2 . By this the 

 amounts of CO, absorbed by the two surfaces of the leaf, as 

 given in the fifth and sixth columns, are calculated from the 

 falling-off in the amounts of baryta that the C0 2 left un- 

 absorbed is able to neutralise. 



The assimilation in this experiment is very vigorous ; 

 in reading three, the whole of the CO, supplied to the upper 

 surface [o'6 per cent, of the air current] is taken up. The 

 intake is nearly equal on both surfaces of the leaf. 



Contrast with this a second experiment made on a 

 leaf of Ampelopsis hederacea which bears all its stomata on 

 the lower surface. 



