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



their branches spreading out and lying parallel to it. These cells 

 may often be found in the deeper tissues of the body and give the 

 impression of their being able to wander between the tissues 

 (Fig. 13). That these cells may be converted into melanophores 

 seems possible. 



That the pigment granules migrate in the fixed pseudopodic 

 processes of the melanophores, instead of an amoeboid extension 

 of and retraction of the processes themselves, is very probable. 

 This migration has been clearly illustrated by Keller and Briicke 

 for the chameleon, Carlton for Anolis, Degner ior Praunus flexuosus , 

 Kahn and Lieben for Rana temporaria and Spaeth for Fundulus 

 heteroclitus . Parker believes that the pigment migration is true 

 for Phymosoma and, further, states that the migration of pigment 

 in melanophores is influenced by light and temperature, either 

 light or low temperature causing a distal migration and absence 

 of light or high temperature causing a proximal migration. 



Although fully agreeing that the melanophores and their 

 processes remain fixed and that their pigment undergoes migration, 

 I am unable to see how any set of factors influence all melano- 

 phores similarly. Under precisely similar conditions the melano- 

 phores of the lateral aspect of the body may contain proximally 

 migrated pigment, whereas the melanophores of the mid-dorsal 

 stripe or melanophores of isolated scales may have the pigment 

 in the terminal branches. In a single animal, in any color state, 

 many exceptions may be found to the rule laid down by Parker. 



Gold chloride preparations repeatedly fail to reveal any nerve 

 endings terminating on the bodies of the melanophores but that 

 these exist seems most probable. Pouchet described a smaller 

 pigment-bearing cell which he termed the erythrophore and which 

 closely resembled the melanophore except that it contained a 

 purplish-red pigment. Briicke overlooked these cells of Pouchet, 

 but according to Keller, the cells only occur on the lateral scales of 

 the chameleon in any great number and are not present in all indi- 

 viduals. Keller described gradation forms, cells containing both 

 brown and red granules in different proportions. Some cells may 

 contain only a few red granules among brown ones while others may 

 contain only a few brown ones, the greater proportion being red. 



Carlton was unable to find erythrophores in the skin of Anolis 

 and denied their existence. I believe that Carlton is correct, for 

 if these cells be present they must be extremely rare. No red pig- 

 ment granules were observed in any melanophores of my sections. 



