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PHYSIOLOGY OF NUTRITION. 



produce per hour at a temperature of 20 C. With careful work, 

 the results of separate experiments will present only very small 

 differences (perhaps 1 mgr.). We may also easily prove that 

 floral structures in general, under similar conditions, respire more 

 vigorously than vegetative organs, e.g. foliage leaves. 



To investigate the relationship between respiration and con- 

 ditions of temperature, we determine successively the amount of 

 Carbon dioxide produced at C., 5 C., 10 C., etc. In experi- 

 ments at C., the respiratory vessel, together with the worm, is 

 placed in a large vessel filled with fragments of broken ice. To 

 obtain accurate results, the temperature must always be regulated 



FIG. 99. Respiration curves. (After Amm.) 



during the passage of the air before introducing the baryta tube. 

 It is very convenient to experiment with seedlings, e.g. seedlings 

 of Lupinus luteus. A large number of seeds are soaked for 

 twenty-four hours, and then germinated in sawdust, contained in 

 suitable zinc boxes, at a temperature of 20 C. (perhaps in a warm 

 chamber). When the seedlings are four to five days old, and have 

 hypocotyls about 2 cm. long and roots about 3 cm. long, they are 

 cleansed from sawdust, and may be used in quantities of 50 gr. for 

 each experiment. Great care must be taken to have at disposal 

 a sufficient supply of very uniformly developed seedlings. The 

 results of the experiments are to be represented graphically in the 

 manner indicated by the upper curve in Fig. 99. At C. the 

 seedlings of Lupinus already respire quite perceptibly. The 



