RESPIRATION AND FERMENTATION 



133 



This may readily be determined by accurate thermometric obser- 

 vations of respiring, in comparison with similar, but non-respiring, 

 tissues. 



Experiment. Fill two non-conducting chambers of 50 to 100 

 cc. capacity with, respectively, actively germinating Peas (or young 

 opening flower-buds), and the same freshly killed by hot water and 

 cooled (in water containing 5 per cent of formalin, to prevent fer- 

 mentation). Provide a carbon-dioxide-absorbing receptacle in com- 

 munication with the chamber (thus promoting growth and respira- 

 tion), and insert the bulbs of two thermometers, the most accurate 

 and sensitive available, into the middle of the seeds; place under 

 conditions favorable for respiration (say 28°-30°), and compare the 

 thermometers at intervals during two or three days. 



Non-conducting Chambers. These are of all degrees of perfection, 

 from the very perfect calorimeters used by various investigators in researches 

 upon this subject, down to make-shift 

 devices of small worth. A form com- 

 monly used for demonstration pur- 

 poses is a glass funnel lined with 

 perforated filter-paper, set over a dish 

 of caustic potash, the whole covered by 

 a bell jar (compare Detmer, 288). 

 Or a tumbler may be used with the 

 seeds resting upon a wire netting over 

 the caustic potash in a flat dish on 

 the bottom. Or inverted small flower- 

 pots, surrounded by felt paper and 

 resting on wire netting over a stick of 

 caustic potash, may be used, as recom- 

 mended in the first edition of this 

 book. Or small beakers, one inside 

 another with cotton between, closed by 

 a cork perforated for a thermometer, 

 and containing a wire netting over a 

 stick of potash, are good. Far better, 

 however, than any of these arrange- 

 ments, and one giving admirable re- 

 sults, either for quantitative studies of 

 some accuracy or for demonstration, is 

 the arrangement shown in the accom- 

 panying figure (Fig. 34). It consists of 

 two Dewar bulbs made for liquid-air 

 experiments, each of two concentric 

 bull s with a permanent vacuum be- 

 tween, and forming, therefore, very per- 

 fect non-conducting chambers. The caustic potash is introduced in a solid 



Fig. 34. — A simple calorimeter for 

 study of the heat relations of 

 respiration; Xi- 



