PHOTOSYNTHESIS AND RESPIRATION. 



99 



produced near the maximum temperature (35 to 45 C.) as 

 at 0C. 



In Broad Bean seedlings the amounts of carbon dioxide produced at 

 30, 35, 40, 45, and 50 are (in milligrams per gramme of fresh 

 weight) 550, 800, 660, 600, and 200. In sprouting Potato-tubers the 

 amounts at 10, 20, 30, 35, 40, 45, 50, 55, and 60 are 120, 220, 

 460, 780, 1020, 1220, 1110, 1030, and 270 milligrams per gramme of 

 fresh weight. 



134. Respiration Experiments. Most of the points 

 just mentioned can be demonstrated by simple experiments. 

 If time allows, some quantitative experiments should be 



Fig. 37. The Arrows show the Direction of the Current of Air, which is drawn 

 through by attaching an "Aspirator" at the left of the Apparatus. The two pieces 

 of glass tubing fitted with stop-cocks may be dispensed with and clips used on the 

 rubber tubing (shown black). 



made, e.g. with the apparatus shown in Fig. 37. In any case 

 make the following experiments : 



* (a) Get nine glass jars of equal capacity. Into 1 pour a little water. 

 Into 2 put some soaked peas, and into the others put an equal weight 

 of the following fresh materials : 3, living roots (cut from seedlings) ; 

 4, mushrooms ; 5, onions sliced in half ; 6, sliced carrots ; 7, pieces of 

 herbaceous leafy shoots ; 8, living woody stems. In 9 put some peas 

 killed by boiling arid then washed with formalin (to prevent growth of 

 moulds and germs). Set all the jars together, after corking them and 

 sealing the corks with vaseline, in darkness. After twenty-four hours 

 lower a lighted taper into each jar in turn, noting the time required 

 for the extinction of the taper in each case. 



