8  SMITHSONIAN    MISCELLANEOUS    COLLECTIONS  VOL.    96 
Shuck,  A.  L. 
1935.    Light  as  a  factor  influencing  the  dormancy  of  lettuce  seeds.    Plant 
Phys.,  vol.  ID,  pp.  193-196. 
ZscHEiLE,  F.  Paul,  Jr. 
1934.  An  improved  method  for  the  purification  of  chlorophylls  A  and  B ; 
quantitative  measurement  of  their  absorption  spectra ;  evidence  for 
the  existence  of  a  third  component  of  chlorophyll.  Bot.  Gaz.,  vol. 
95,  no.  4,  pp.  529-563- 
