478 



C. A. West 



Table 2. Ethylenic double bonds from permanganate 

 reduction studies. 



B spectrophotometer. The absorbancy of an unknown relative to 

 that of a standard (absorbancy of blank subtracted from each) was 

 used to calculate the number of double bonds per unit weight. Table 

 2 shows the results for A^, Ao, and A4, bean factor I, and bean factor 

 II with A3 taken as a standard. 



Determination of Exocyclic Methylene Groups 



A procedure adapted from Lemieux and von Rudloff (5) was em- 

 ployed for the micro-estimation of terminal methylene groups of the 

 type reported to be present in A^, A3, and A4. The procedure is 

 based on conversion of the methylene group to formaldehyde by 

 means of a periodate-permanganate reagent followed by the colori- 

 metric estimation of the formaldehyde produced with a chromotropic 

 acid reagent. Table 3 summarizes the results obtained with this 

 method for the fimgal gibberellins and the bean factors. The yields 

 are in the range of those found by Lemieux and von Rudloff. These 

 results suggest the presence of exocyclic methylene groups in bean 

 factor I and bean factor II. However, this interpretation is tentative 

 since A2 seems to yield formaldehyde even though it is thought not 

 to have such a group. 



Table 3. Determination of exocyclic methylene groups. 



