PLATE 1 



EXPLANATION OF FIGURES 



In figures 1 to 10 are shown five sets of brook trout embryos which were ex- 

 posed to the action to 0.2 M solutions of Kl, KNO3, KBr, KCl, and K2SO4, 1 to 

 5 for an interval of fifteen minutes, and figures 6 to 10 for a period of three 

 hours. 



1 The melanophores were completely contracted in Kl. 



2 The contraction was not as pronounced in. KNO3. 



3 In KBr the melanophores had longer processes than in the two preceding 

 solutions. 



4 In KCl the processes were more distinct and showed the finer arboriza- 

 tions. 



5 An exposure of fifteen minutes to K2SO4 produced no observable change 

 in the melanophores. 



6. After an exposure of three hours to Kl the melanophores showed a distinct 

 secondary expansipn. 



7 In KNO3 an exposure of three hours produced a less extensive secondary 

 expansion than Kl. 



8 In KBr the processes were very much shorter than in Kl and KNO3. 



9 After three hours in KCl the melanophores were still spherical, but there 

 was a suggestion toward a peripheral migration of the pigment as indicated by 

 the swollen condition of the cells. 



10 After three hours in K2SO4 there was no expansion of the melanophores. 



11 All melanophores contracted, photograph taken after twenty-four hours 

 of exposure to Picrotoxin. 



12 The melanophores expanded after severing the tail in an individual which 

 was exposed to Picrotoxin for twenty-four hours. Photograph taken five min- 

 utes after cutting. 



13 All melanophores contracted during the period of Strychnine con- 

 vulsions. 



14 Showing the expansion of the melanophores after the strychnine convul- 

 sion had subsided. 



15 The contracted and expanded melanophores as they occurred in 0.0025 

 per cent curarn 



192 



