476 C. A. West 



cent ethyl acetate in chloroform, 400 ml. of 80 per cent ethyl acetate 

 in chloroform, and 400 ml. of ethyl acetate. Forty ml. fractions are 

 collected and aliquots are tested for activity. Bean factor II is eluted 

 primarily in those fractions obtained with 40 per cent ethyl acetate 

 in chloroform as the developing solvent and bean factor I is eluted 

 by 60 per cent ethyl acetate in chloroform as the developing solvent. 

 Under identical conditions A^ and A3 are eluted with the latter de- 

 veloping solvent. Such columns have been used to demonstrate the 

 presence of gibberellin-like substances in crude extracts and also as a 

 terminal step in purification. 



Biological Properties 



The biological properties of bean factor II are discussed more 

 completely by Phinney elsewhere in this volume (7). In quantitative 

 assays on dwarf mutants of maize, bean factor I and A^ show the 

 same activity on a weight basis. The growth response of maize mu- 

 tants dwarf-2, dwarj-3, dwarf-5, and anther-1 to bean factor II is equal 

 to or greater than the response to an equivalent amount of A3, the 

 most active of the fungal gibberellins. However, bean factor II is 

 less than 5 per cent as active as A3 for the dwarf-1 mutant. Thus, bean 

 factor II is quite distinct from A^, Ao, A3, and A4 in its biological 

 properties. 



Neutral Equivalent 



A spectrophotometric micro-method for the determination of the 

 neutral equivalent weight of carboxylic acids was developed. A 

 known weight (about 0.05 microequivalent) of acid to be tested was 

 dissolved in 3.50 ml. of a freshly prepared solution of the sodium salt 

 of jjhenolsulfonphthalein (phenol red) (3 mg. per 100 ml. of boiled 

 distilled water). Care was taken to exclude atmospheric carbon di- 

 oxide. The absorbancy at 550 lUfj. was measured in a Beckman B 

 spectrophotometer for (1) a reagent blank (no acid added), (2) the 

 solution of an unknown acid, and (3) the solution of a standard acid. 

 The absorbancy of sodium phenolsulfonphthalein decreases at 550 

 ni/i, in the presence of an acid due to the conversion of the indicator 

 from the base to the acid form. The magnitude of the decrease is a 

 function of the equivalents of acid added and can be standardized by 

 reference to a standard acid. 



Determinations of the neutral equivalent of bean factor I by this 

 technique with A3 as standard^ gave values of 370 and 340 (average 

 = 355) and values of 380 and 340 (average =r 360) were obtained for 



' Reference samples used in these studies were kindly supplied as follows: 

 A„ A2, and A, — Prof. Y. Sumiki, University of Tokyo, Tokyo, Japan, and A, and 

 A:, -Dr. Frank Stodola, Northern Regional Research Lab., USDA, Peoria, 111. 



