giving no response (No, 143) and the second giving a slight response 

 {No„ 181), More attention was directed to the anion exchange colunnn, 

 for it seemed to adsorb the attractant in several experiments as shown 

 by moderate to strong (X and XX) positive responses with a water, 

 dilute sodium hydroxide, or dilute ammonium hydroxide elutant (Nos, 

 182, 185, 193, 194, 201, 208, 213), Up to this stage of the study, the 

 eluate failed to give a response in only two tests (No, 196 and 223) in 

 which a response was expected on the basis of the preceding results. 

 The filtrate, on the other hand, gave either a weak positive response 

 or no response (NoSo 179, 200)„ 



It was clear, however, that the attractant was held very 

 "loosely" on the anion exchange columnp appearing nnostly in the 

 first portion of the water or weak base eluate (compare Nos. 185, 

 186, 187; Nos, 208, 209, and 210; 213,214; 246, 247 and 248), The 

 weak affinity (possibly not a true ion exchange) explains the failure of 

 complete separation in some of the above experiments, and may have 

 contributed to certain inconsistencies to be reported later. 



Chemical tests were run on the attractant in its purest 

 form yet attamedj, namely, that portion of the water eluate from the 

 anion excheinge column which was soluble in absolute ethyl alcohol 

 (NOo 201)„ Both the Biuret and Ninhydr in tests were positive, show- 

 ing the presence of the ainide link„ The Xanthoproteic reaction was 

 positive, showing the presence of the benzene ring, A test for phos- 

 phorus was positive, but a test for sulphur was negative. 



In subsequent experiments which were run from the latter 

 part of December on through the winter, the results became erratic. 

 There was difficulty in obtaining meaningful and consistent results 

 with the various chemicals used in purification, and also with the 

 anion and cation exchange colunnns used in fractionation. For ex- 

 ample, when barium acetate was substituted for lead acetate to pre- 

 cipitate the proteins and the filtrate was treated with sulphuric acid 

 rather than hydrogen sulphide gas to precipitate the barium as a 

 sulphate, no response was obtained (No, 211) , Also there was no 

 response for the solution that resulted when the protein precipitate 

 of Noo 211 was dissolved with nitric acid and the barium precipitated 

 as a sulphate and filtered off (No. 212), The loss of activity, if real, 

 may have been due to either destruction or CO precipitation of the 

 attractant by the barium ion or by the sulphuric or nitric acid. That 

 the barium ion was not responsible is shown by the series of experi- 

 ments depicted in figure 11, An alcohol extract of skipjack flesh was 

 acidified and treated with phosphotungstic acid to precipitate the 

 purines. Barium acetate (in one experiment) and barium chloride (in 

 another) was used to precipitate the phosphotungstic acid and the 



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