REACTIONS OF MELANOPHORES 



199 



TABLE 2 



The reactions of the mclanophorea of normal and eyeless larvae to light and 



darkness 



utes) begin to expand, though it is sometime before expansion is 

 completed, the time varying between one and two hours for the 

 normal larvae, and between two and three hours for the eyeless 

 (figs. 1 and 2). If, after the melanophores have expanded, they 

 are transferred back to darkness, the melanophores contract 

 (figs. 3 and 4). This reaction does not begin so quickly as that 

 to light, and it takes longer to be completed, between two and 

 three hours for the normal larvae, and between four and five 

 hours for the eyeless. 



It is clear then that, as in A. punctatum, there is no differ- 

 ence between the responses of the melanophores of normal see- 

 ing and eyeless larvae of A. tigrinum. In light they expand 

 (figs. 1 and 2), in darkness they contract (figs. 3 and 4). This 

 reaction always take place, from the time the melanophores are 

 first responsive to light and as long as they have been examined, 

 the reactions of the melanophores having been observed in larvae 

 ranging in length from 20 to 70 mm. It may be mentioned in 

 passing that, as the larvae grow older and the number of melan- 

 ophores increases, the reactions take longer and are less com- 

 plete. 



Due to the fact that, although the reactions of the melano- 

 phores of A. punctatum and A. opacum was to expand in light 

 and contract in darkness, the state of the melanophores of see- 

 ing larvae, when these were kept for some time in light or dark- 

 ness respectively, was different, a distinction was made be- 



