PHYSIOLOGY OF CHROMATOPHORES OF FISHES 533 



During the summer of 1911 the privilege and use of a table at the 

 United States Fisheries Laboratory, Woods Hole, Massachu- 

 setts, were granted by Hon. G. M. Bowers, which greatly facili- 

 tated the work. 



2. REACTIONS TO SALT SOLUTIONS AND DISTILLED WATER 

 1. Ejects of sea-water and distilled water 



Among the first experiments performed with the scales taken 

 from the living fish were trials made to determine the effect of 

 sea-water^ upon the chromatophores. When scales were re- 

 moved from a light female and immersed in sea-water a very 

 slight expansion of the dark pigment could be seen upon imme- 

 diate examination. This expansion occurred in all the melano- 

 phores of a single scale simultaneously. In no case was it so 

 great as is the expansion in the melanophores of a normal dark 

 fish. When scales from such dark fish were placed in the same 

 sea-water there was no visible change. They remained dark 

 with completely expanded melanophores for some hours (de- 

 pending upon the temperature of the sea- water) . Eventually 

 they began to degenerate from the expanded state. This de- 

 generation was perfectly characteristic. The pigment in the 

 processes of the melanophores which, in the normal, living, 

 expanded condition, is seen as narrow, continuous, dark lines, 

 became broken up into small, spherical or ovoid masses and the 

 melanophores thus gradually lost their individual contours. 



The following experiment illustrates the extent of the initial 

 effect in sea-water. 



March 1,1911 



1.33 P.M. Scales were removed from a 10 cm. light female and placed 

 in sea-water. Only a slight outward migration could be 

 seen and this was not active. 



2.11 and 2.57 p.m. Other scales from the same fish showed the same 

 sluggish behavior as the first set. In all these cases the 

 shifting of the pigment had ceased three minutes after the 

 immersion in sea-water. T. = 17°C. 



2 This sea-water was taken from the marine aquaria in the Museum of Com- 

 parative Zoology at Cambridge, Mass. 



