554 R. A. SPAETH 



expansion occurred. If scales with completely expanded mel- 

 anophores were :mmersed in the former solution a very slow con- 

 traction followed. Depending upon the initial condition of the 

 melanophores this solution may thus cause either an expansion 

 or a contraction. If scales were taken directly from a light fish 

 and immersed in this solution, a wide expansion of the melano- 

 phores occurred (due, in part, to the removal of the nervous 

 tonus). This was followed at once by a contraction. In the 

 following experiment contracted melanophores could not re- 

 main so but their expansion was not complete. Similarly ex- 

 panded melanophores contracted partially. 



February 1 4, 1913 



4.14 P.M. Corresponding scales from the sides of a 9 cm. male were 

 removed to solutions of 0.1 M KCl and 0.1 M NaCl re- 

 spectively. 



4.16 P.M. Melanophores contracted in the KCl and expanding in the 

 NaCl solution. 



4.31 P.M. Three scales from each set were changed to identical solu- 

 tions (7 cc. 0.1 NaCl + 1 cc. 0.1 KCl). 



4.51 P.M. A few peripheral melanophores of the set started in KCl 

 showed a slight expansion. All three scales of the otjier 

 set showed a partial but not a complete contraction. 



5.06 P.M. All three scales in the KCl set showed all the melanophores 

 partially expanded. All in the NaCl set were partially 

 contracted at this time and slightly darker than the KCl 

 set, though distinctly lighter than the control scales in 

 NaCl. 



5.36 P.M. The KCl set sHghtly darker than the NaCl scales. T. = 

 21.2°C. 



10.00 A.M. (February 15, 1913) Both sets showed a partial contrac- 

 tion. No difference between them. 



Experiments with mixed solutions of other salts of potassium 

 and sodium chloride showed a similar slowing down of the normal 

 potassium contraction by the addition of sodium chloride in a 

 given proportion. 



June IS, 1912 



8.40 P.M. Scales from an 8 cm. female were removed to a 0.1 M 



NaCl solution, 

 9.31 P.M. Six scales were transferred to a solution of 9 cc. 

 NaCl 0.11 M + 2 cc. 0.1 M KSCN. 



9.41 P.M. All these scales showed the melanophores still expanded. 



