198 LECTURE XI. 



2. With germinating seeds (de Saussure). 



24 grains of Wheat were left for 2 1 hours in a closed receiver contain- 

 ing air. 



Composition of the air. At the commencement. At the end of the experiment. 



N 148-84 c.c. 148-32 c.c. 



O 39'86 37 "44 



CO, o-oo 2-47 



188-70 ,, i88-2 3 



3- With leaves in air (Boussingault). 



Duration of O CO 2 



expt. Plant. absorbed. evolved. 



31 hours Oleander i8 - 3 19-60 c.c. (several leaves) 

 24 do. 8-40 8" 10 (one leaf) 

 do. 2'8o 2'6o 



ii do. 2 - oo i "80 



4 do? 1-31 1-57 



It would be easy to add to this list out of the very large 

 number of experiments of this kind which have been made, 

 but further illustration is unnecessary. 



There is evidence to shew that variations of temperature 

 affect the relation between the volumes of the gases ab- 

 sorbed and exhaled. As regards the absorption of oxygen, 

 it has been observed by von Wolkoff and Mayer, that this 

 takes place to a slight extent at a very low temperature, and 

 that it increases as the temperature is raised up to a certain 

 degree ; any further rise of temperature is accompanied by a 

 diminished absorption of oxygen. 



TropcEolum majus. 



5 seedlings absorbed o'6o c.c. O per hour at a temp, of 22*4 C. 



077 27-0,, 



076 30'5% 



0-77 30-0,, 



1-04 35'o,, 



0-91 38-2,, 



Wheat. 



4 seedlings absorbed o'io c.c. O per hour at a temp, of 15 '6 C. 



,, 0-038 4-4,, 



0-067 ,,' 9'8% 



0-088 15-4,, 



0-022 0-3,, 



0-016 o-i,, 



