RESPIRATION AND FERMENTATION 



127 



vacuum, without the use of an air-pump, has been described by L. MURBACH 

 in School Science, i, 1901, 25, and his method, somewhat modified, is as 

 follows: Treat each of two glass tubes of about 4-5 mm. bore and 15 cm. 

 length as follows: seal one end and push to this end two germinated Oats 

 or Barley grains held in place by a spring-coil of wire; fill 

 the tube one-third full of water previously boiled (to expel air) 

 and cooled, and then draw out the open end in the flame to 

 a slender point; holding the tube slightly inclined from the 

 vertical, boil the water near its surface, which will not, 

 because of the low heat-conductivity of water, injure the 

 seeds; whilst the water is actively boiling, thus replacing all 

 air in the tube by steam, quickly drop the point of the tube 

 into the flame and seal it. When cool the condensation of 

 the steam will leave a vacuum in the tube, the perfection of 

 which may be tested in part by the "hammering" of the 

 water when the tube is shaken lengthwise, and in part by the 

 rise of water when, at the close of the experiment, the sealed 

 point is broken under water (by pincers). In one of these 

 tubes, the control, the point should now be broken, air read- 

 mitted, and the tube resealed; then both should be stood side 

 by side (Fig. 32), seeds upwards under good growth condi- 

 tions, and the comparative behaviors of the two sets watched. 

 (c) Tubes, containing seeds, similar to those just described 

 could be exhausted of air by an air-pump, and then sealed 

 by the Bunsen flame, (d) The seeds may be introduced 

 through a column of mercury in a tube over 76 cm. long, 

 thus coming to lie in a Torricellian vacuum (compare DETMER, 

 2 7S)- ( e ) The air may readily be displaced by hydrogen 

 from a bottle containing germinating seeds, either by simple 

 buoyant displacement, or by expulsion of water over the 

 pneumatic trough. (/) The seeds may be placed in the 

 chamber of a respiroscope, the open end of which is placed 

 in pyrogallate of potash; this will rapidly absorb the oxygen 

 from the instrument, rising of course to take its place. 



The absorption of carbon dioxide with release 

 of oxygen, shown by the foregoing experiments, 

 recalls the similar phenomena in animals, where CONTAINING 

 they are known to be associated with the vitally GERMINATED 

 important process called Respiration. This resem- SEEDS A ND 



WATER ' X i 



blance, the student will find on further inquiry, is 



not one of accident, but of relationship, and the process is 



identical in the two kingdoms. 



The foregoing study of the process has been purely qualita- 

 tive, but we must now consider it quantitatively, not only be- 



