Fig. 6. All tubes contain watery solutions frozen up to the middle. 

 From left to right, first: 0.0001 Ai rhodamin B. Second: rhodamin B and 

 0.001 M thiamin HCI. Third: 0.001 M riboflavine phosphate sodium, 

 no Oi. Fourth: same and atmospheric oxygen. Fifth: same plus 0.001 

 M KI. 



