Respiration, Aeration, and Fermentation 301 



somewhat more than 200 grams of 

 field peas or wheat, and after soaking 

 weigh out two lots of 100 grams each. 

 Kill one lot by immersing it in boil- 

 ing water for about 10 minutes, then 

 place both the killed and the living 

 seed in separate cheesecloth bags and 

 immerse each in formalin solution 

 (1 part to 600 parts of water) for 

 15 minutes. Take the bags from the 

 formalin and dip them into boiled 

 water with as little handling as pos- 

 sible (the water should be at room 

 temperature or at the temperature of 

 the incubator to be used). Have 

 thoroughly cleaned by the chromic 

 acid mixture two double-walled, vac- 

 uum, silvered flasks or Dewar bulbs 

 of 250 cc. capacity (Figs. 72 and 73). 

 Sterilize these also by rinsing with 

 the formalin solution above indicated. 

 Provide each flask with a short vial 

 or small dish of KOH protected from 

 tipping over by a wire cage lowered 

 by a string, also previously steri- 

 lized as to the exterior. Pour care- 

 fully each lot of seed into a separate 

 Dewar bulb, insert a standard ther- 

 mometer, previously dipped in forma- 

 lin and rinsed, and plug the flasks 

 with wool. Wrap the flasks well with 

 felt or woolen cloths and place them 

 at a temperature as constant as pos- 

 sible. Ten minutes later take the 

 temperature of each, and at intervals 

 of 12 hours for several days, or until 

 there is a rise of temperature in the FIG. TS.^Oxygen and growth. 



