523 



amphibians are permanent. The evidence for a similar condition in 

 fishes and reptiles is most fragmentary and contradictory. Golovine 

 (: 07, p. 864) has stated: "Cependant, durant tous ces changements 

 nous n'avous jamais pu observer le mouvement des grains de pigment 

 dans les paijjties interieures de cytoplasma, mouvement mentionne par 

 BRtJCKE et; d' autre auteurs. " 



In a paper now in press it has been shown that in fresh pre- 

 parations of the scales of the minnow, Fundulus heteroclitus, the 

 migration of the pigment within the melanophores may be completely 

 controlled by appropriate mixtures of sodium and potassium salts. It 

 was a comparatively simple matter to carry out experiments similar 

 to those of Kahn und Lieben ( : 07). 



. V «iL^ i- ^ 



Fig. 3. The same melanophores reexpanded in a 0.1 molecular sodium 

 chloride solution. The processes are identical with those appearing in the first figure. 



In making these photographs no cover-glass was used. The illumination was 

 by means of a single Nernst glower (110 volt). 



When scales are removed from the fish, the superficial melano- 

 phores and xanthophores are seen to lie in the derma between the 

 scale and the epidermis. The immersion of these scales in a 0,1 

 molecular sodium chloride solution produces a lasting expansion of 

 the melanophores. A portion of the scale was now selected in which 

 a melanophore had its processes in approximately the same plane. 

 After carefully locating the cell upon the scale, which was easily- 

 done by counting the number of growth rings, a photograph was taken 

 of the expanded phase. The scale was then transferred to a mixture 



