SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 107, NO. 17, PL. 8 



Inhibition by Vapor of acrolein 



Seeds planted on garden loam (upper row), 1.5-percent agar-water gel 

 (middle row), and filter-paper-wrapped porous silica wicks (lower row). At 

 the higher concentration {0.014 percent by volume of air) the seeds were killed 

 and did not recover on subsequent exposure to pure air. Photographed 4 days 

 after planting. 



