THE METABOLISM OF PLANTS. 199 



With regard to the evolution of carbon dioxide, it has been 

 found that it is smaller at low temperatures than the absorp- 

 tion of oxygen, and more considerable at higher temperatures. 



Pedersen determined the amount of CO 2 evolved by Barley-seedlings : 



at 4-5 C. they evolved per hour 9*5 mgr. CO 2 . 



8-1 10-8 



, 1 5 '3 16-5 



99 l8 ' 99 99 24-3 99 



Similar determinations were made by Rischawi with Wheat- seedlings: 

 at 5 C. they evolved per hour 3*30 mgr. CO 2 . 

 ii 10 99 5*28 



15 99 9'9o 



,,20 12-54 



,,25 17-82 



99 30 22-04 



,,35 28-38 



4o 37-6o 



Dehe'rain and Moissan experimented with leaves : 



loo grmes. of leaves of Smart's alba 



evolved in 10 hours 0*240 grme CO 2 at a temp. 14 C. 

 99 99 99 72o 31,, 



99 99 99 99 ' 6 36 40 



Pinus Pinaster 0-031 o 



0-058 8,," 



99 99 99 99 O'OQS 15,, 



0703 30,, 



99 99 99 99 l '333 99 99 4^99 



It appears that in the experiment with leaves, of Sinapis alba at 

 40 C., the optimum temperature had been surpassed. 



We may further illustrate this point by some of Moissan's results. 



