Furfuryl mercaptan (Nos. 231, 241) 



Coumarin (No„ 249) 



Methyl anthrcinilate (No. 250) 



Meat flavor (No. 253) 



Pineapple juice (No, 168) 



Eosin B (No. 36) 



Methylene Blue (No. 38) 



None of the above substances gave a positive response 

 which could be verified. In some, however, there appeared to be a 

 sensing of the substance as will be discussed below. 



Among the amino acids, serine appeared to give a weak 

 positive response in one tank experiment (No. 51) ajid a very weak 

 positive response in another (No. 56). In three pond experiments, 

 there appeared to be a sensing of the material in one (No, 101) but not 

 in two others (Nos. 104 and 108), On the sanne day on which the fish 

 appeared to sense the serine in the pond (No. 101) they also appeared 

 to sense asparagine (No. 102) and arginine (No. 103), suggesting that 

 they were in a particularly responsive condition. On another occasion 

 they appeared to sense methionine (No. 157). Apparently the fish were 

 aware of the presence of the substajices but the slight reaction seemed 

 to be one of curiosity rather than attraction: certainly it lacked the 

 features of a typical response. 



This same sensing of material was noted in the case of 

 certain strong-smelling aromatics, e.g., anethol (No, 22), "meat 

 flavor" (No. 253), and particularly furfuryl mercaptan (Nos. 231 and 

 241). The first substance, which has a licorice smell, is the active 

 ingredient of oil of anise, a reputed fish attractant; the second is a 

 strong, spicy, pleasant-smelling artificial flavor; the third is a- very 

 foj.1- smelling chemical of great potency. A similar response was 

 noted with odorless vitamins, B (No. 166) and acetyl choline chlo- 

 ride (No. 192), and also with ordinary pineapple juice (No. 168). 

 Again, however, the response seemed to be one of curiosity. 



The series of experiments with adenosine, adenosine conn- 

 pounds, and adenylic acid was conducted in an attempt to determine if 

 the attractive substance was one which is present in mammalian mus- 

 cle. That it might be was suggested by chemical tests of the attract- 

 ant (see later) which showed the presence of phosphorus and the amide 



36 



