PHYSIOLOGY OF CHROMATOPHORES OF FISHES 545 



Similar trials were now made with KI solutions. The effect 

 was again a contraction of the melanophores. The time of this 

 contraction was the same as in the chloride and bromide solu- 

 tions. No constant difference was observed. A secondary ex- 

 pansion occurred here also but even sooner than in KBr. 



After the probable position of the iodide had been established 

 other experiments were made comparing the action of only the 

 KBr and KI since the chloride-bromide sequence had previously 

 been determined. 



April 36, 1913 



Scales from a 9.5 cm. ft^male were put into a 0.1 M NaCL solution. 

 After eighteen minutes 2 matched pairs were immersed in equal volumes 

 of 0.2 M KBr and KI re.spectivcly. Thirty-five minutes later the 

 scales in the KI showed a decided expansion of the; melanophores while 

 in the KBr they were only slightly expanded. The time of contraction 

 in both cases was one and one-half minutes with no noticeable differ- 

 ence in the two solutions. T. = 20°(^. 



Thus as regards the maintainance of irritability the anions of 

 these potassium salts showed this order, 



Cl>Br>I 



Experiments with KNO3 showed clearly that the cytolytic ac- 

 tivity of its anion was intermediate in character between the 

 Br~ and I". As in the case of the potassium iodide its action 

 was compared with the three halogens simultaneously to de- 

 termine its approximate position and then matched scales were 

 run against each other in isionic solutions of both the KBr (on 

 one side) and the KI on the other. Thus 



May 8,1912 



11.09 A.M. Scales from a' 9 cm. female were removed to a 0.1 M NaCl 

 solution. 



11.57 A.M. ' 4 sets of 4 scales each were immersed in 6 cc. of 0.18G M 

 KCl, KBr, and KI, and G cc. of 0.2 M KNO.-, respectively. 

 All the melanophores were contractcnl in two and one- 

 half minutes. 

 1.35 P.M. The KI, KNO3 and KBr solutions all ^howed some expanded 



melanophores. None were expanded in KCl. 

 3.00 P.M. The four scales showing the most expanded melanophores 

 in the four solutions were fixed in 95 i)er cent alcohol. 



