on the column and which was eluted or washed from it with various 

 solutions such as water, weak acids, weak bases, alcohol, acetone, 

 etCo 



In a series of experiments with columns of activated 

 alumina, zeolite, and activated carbon (Nos, 149 to 154) positive 

 responses were obtained from both the filtrate and (water) eluate of 

 the alcohol extract of skipjack flesh. However, the attractant appeared 

 to be adsorbed most on activated alumina (No. 150) and least on acti- 

 vated carbon (No„ 153)o Adsorption on activated alunnina was obtained 

 m two additional experiments (Nos„ 156 and 165), but complete separa- 

 tion of the attractant was not achieved (Nos, 155 and l62)o Attempts 

 at fractionation with alumina were abandoned in favor of anion and 

 cation exchange columns c 



Small white crystals which appeared in the (acetone) 

 eluate from the activated carbon column, when dissolved in water, 

 appeared to cause a positive response (No„ 159), Further prepara- 

 tions gave no response (No, 167) and a doubtful response (No. 171), 

 It was concluded that the positive responses were apparent rather than 

 real and that the white crystals were not attractive. The attractive 

 substance, for the most part, appeared in the filtrate from the carbon 

 columno Thus either mixing or boiling activated carbon with the ex- 

 tract or paissing the extract through a carbon column would remove 

 certain inactive substances and constitute a stage of purification. 

 This procedure was followed in some of the later preparations. 



Another step in purification was the removal of fatty acids 

 and related compounds which were soluble in petroleum ether or 

 acetone. Van Weel (1952) found that the attractant was not soluble in 

 petroleum ether. This finding was verified (Nos. 18, 142, 175, 177, 

 eTc„)„ It was also found that the attractant was not removed by ex- 

 traction with acetone (No, 142). 



Still another step in purification was the removal of 

 inactive proteins by precipitation with tannic acid (No. 215), lead 

 acetate (No, 197; Nos, 200 to 206; etc.), or barium acetate (Nos, 211, 

 212, 225) and the removal of, purines and similar compounds as silver 

 salts (Nos, 183, 184) or with phosphotungstic acid (No^ 193, etc.). 



Some of the above steps in purification either preceded or 

 succeeded fractionation by adsorption on anion or cation exchange 

 resins. Mciny different experiments, employing one to several suc- 

 cessive stages of purification, were conducted. Two typical series 

 only will be discussed to illustrate the procedure and results. Others 

 may be followed from data given in the Appendix. 



42 



