698 /. P. Nitsch and C. Nitsch 



line ones (8.0). Thus a first method to separate the water-sohible in- 

 hibitor from the growth-promoting principle is to partition the aque- 

 ous extract with ethyl acetate at an acid pH (Figures 5 and 6). 



Adsorption on charcoal. A second method, which gave even slightly 

 better results in that it apparently isolated a greater quantity of the 

 growth-promoting material, made use of activated charcoal. The 

 crude juice, or an aqueous extract, was treated with activated char- 

 coal and filtered. The inhibitory principle remained in the filtrate 

 while most of the growth-promoting activity remained adsorbed on 

 the charcoal. The growth-promoting principle was eluted with boil- 

 ing methanol. Since this eluate contained also substances of the auxin 

 type, it was further partitioned between ether and water at pH 3.0 

 (HCl), the auxins moving to the ether layer and the TJF remaining 

 in the water layer. 



Further Purification of the TJF 



Further purification of the growth-promoting principle was 

 achieved through the use of paper and column chromatography. \\'ith 

 the mixture ethyl acetate (9) -\- glacial acetic acid (3) -|- HoO (4) (v/v), 

 three different active components could be separated on either paper 

 strips or cellulose columns, the Rf values being: substance I (0.15), 

 substance II (0.45), and substance III (0.95). 



GROWTH FACTORS IN TOMATO FRUITS 



The various techniques which had been briefly mentioned here 

 have not yet led to the identification of any single compound which 

 would be responsible alone for the biological properties of tomato 

 juice. Instead, the TJF seemed to split into numerous constituents, 

 many of which had a small activity on one or the other biological tests. 



Inhibitors 



Even the inhibitory effect of TJ was found to be due to at least 

 three groups of substances, namely: 



Petroleum ether-soluble inJiibitor. This was extracted with pe- 

 troleum ether from either dried or fresh material and was present in 

 green and in ripe tomatoes. As was already reported by Konis (12), 

 this inhibitor is partially eliminated by autoclaving. It is probably 

 an essential oil. 



Ether-soluble inhibitors. This fraction Avas reported by Larsen (14) 

 and Hemberg (7) to contain substances which inhibit curvature in 

 the Avena test. One of these inhibitors may be salicylic acid which 

 was found to move at the same position as the inhibitory ether frac- 

 tion on paper chromatograms and which was found to inhibit the 



