60 

 40 

 20 



60- 

 40- 

 20 



60 



401 



20 



60 

 40 

 20 



60- 

 40- 

 20- 



60- 

 40- 

 20- 



A 



-10 



.-8 



7 



.--6 



't'^Wi 



--^//-. 



B 



^^^""^m^ 



-10 



la. 



8 





5 ._-.J-,,^.__.5 



^-^ 



"J~ 



-^^C^- 



-2 



^"^^^"'"^ ""ll^^'^^^"""' 



—I 1 r- 



0.2 04 0.6 0.81.0 



r 



0.2 04 0.6 0.8 1.0 



Fig. 3. Histograms showing the chromatographic separation of substances 

 affecting germination extracted from lettuce seeds germinated in water, in 



coumarin or in thiourea. 

 A — acidic extracts; B — neutral extracts; 1 — dry seeds; 2 — seeds 

 imbibed for 2 h in water in the dark; 3 — seeds imbibed for 4 h in water 

 in the dark ; 4 — seeds imbibed for 12 h in water in the dark ; 5 — coumarin 

 control; 6 — seeds imbibed for 2 h in coumarin; 7 — seeds imbibed for 

 12 h in coumarin; 8 — thiourea control; 9 — seeds imbibed for 2 h in 

 thiourea; 10 — seeds imbibed for 12 h in thiourea. The broken lines give 



the water controls ^^. 



