110 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Chairiceleon, Fundulus heierocUius , Rana temporaria, and other 

 color-changing animals. 



5. The color changes in Anolis depend upon the reciprocal 

 physical action of four layers of the skin: the epidermis, the 

 yellow oil droplet layer, the leucophore layer and the melano- 

 phores. The physical characters making possible light inter- 

 ference and absorption, and the mixing of transmitted and 

 reflected rays, modified by the migration of pigment to different 

 positions in these layers, result in the varieties of color apparent 

 at the surface of the skin at different times and on different locali- 

 ties of the body. The red coloration of the throat-fan is due to a 

 rich capillary plexus and to the presence of a red coloring matter 

 in the deeper layers. The effect of vaso-dilatation is also apparent 

 in the pinlc stripe noted occasionally along the mid-dorsal line. 



6. The oil droplet layer and the leucophore layer in general 

 remain fixed and the various color states depend on the migration 

 of the pigment granules in the fixed processes of the melanophores. 

 Maximal proximal migration of the pigment is associated with 

 yellow, while maximal distal migration produces dark mahogany 

 brown. In the emerald green state the pigment lies in the primary 

 and larger branches of the melanophores. Further distal migration 

 is associated with bluish-green or slaty-gray color states depend- 

 ing on the degree. 



