222 WILLIAM EUGENE PICKLER 



retain their activity without appreciable change in stored dry seeds for 

 20 or more years, that is long after the power of germination has been 

 lost, which takes place in wheat after 11 to 16 years, barley 8 to 10 

 years, oats 5 to 9 years, maize and rye over 5 years. The life of the 

 stored seeds is largely dependent upon the climatic conditions, a dry 

 climate favoring longevity. 



The experiments of Kolkwitz (1901) on the respiration of 

 barley as affected by moisture content are of interest, since it is 

 through the hydrolization of starch by diastase that active and 

 long continued respiration depends. Kolkwitz found that 1 

 kilo of barley with a moisture content of 10 to 11% gives off in 

 24 hours from | to 1.5 mgm. of CO>. In barley containing 20% 

 water the respiration is markedly higher than could be attained 

 through any increase of temperature in air-dry barley, that is, 

 barley containing 10 to 11% water. One kilo of barley of 33% 

 water content gives off in 24 hours 2000 mgm. of C0 2 , and this 

 quantity of C0 2 may be increased ten fold by an increase in 

 temperature and an increase in the quantity of oxygen supplied. 

 Duvel (1904), Babcock (1912), and others have had similar 

 results. 



2. MATERIALS AND METHODS 



JoSa. ca^JxvX i* ~w**.l w a ter content and temperature are the two factors, the effect 



^jtLO^L «u. (*******¥' \ of which on the diastase content of the resting seed it was planned 



%\x- rj uK*£fc*.»<* *nto study. Both factors must be controllable within narrow 



Y° eft g^£-f-- * limits over considerable periods of time. Much time was used 



in working out methods by which the temperature and more es- 

 pecially the moisture content was maintained through longer 

 periods of time and with relatively slight variations. Kolkwitz 

 (1901) experienced a similar difficulty. He says, 



Die Hauptschwierigkeit dieser Untersuchungen lag in der Wahl 

 einer geeigneten Methode, denn ein Schwanken im Feuchtigkeitgehalt 

 der hygroskopischen Korner wahrend des Versuches hatte die Genauig- 

 keit der Resultate ernstlich in Frage gestellt. 



Manshury barley obtained from Vaughan's Seed Store, Chi- 

 cago, was first used. It was given up and White Hulless sub- 



