1922] ROBBINS—ROOT TIPS 79 
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Rossiys, W. J., The eubidia of excised root tips and stem tips under 
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Witiams, R. J., Vitamines and yeast oe Jour. Biol. Chem. 46: 
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. WEBER, F., dicmkone in Pflanzenreich. Naturwiss. Wochenschr. 35: 
241-253. 1920 
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