32 



Scientific Proceedings (6i). 



contract, a low temperature (below 12°) causes them to expand, 

 both in the intact skin and in isolated pieces. These high and 

 low temperatures inhibit the effects of light and darkness respec- 

 tively. Intermediate high temperatures (above 32 0 ) hasten the 

 rapidity of the contraction and retard that of the expansion of 

 the melanophores, while intermediate low temperatures (between 

 12 0 and 17 0 ) have the opposite effects. 



Chloretone (0.02 per cent, and 0.0 1 per cent.) causes the 

 melanophores in the intact skin and in isolated pieces to expand. 

 Curare (0.2 per cent, and 0.1 per cent.) and atropin sulphate (1 per 

 cent.) have the same effect when larvae are placed in them, but 

 have no effect on the melanophores of isolated pieces of skin. 



The injection of a I per cent, solution of curare into the body 

 cavity does not affect the primary responses of the melanophores 

 to light and darkness, although the larvae are rendered immotile, 

 nor does the injection of a 0.01 per cent, solution of nicotine have 

 any effect. On the other hand the injection of a 1 per cent, 

 solution of strychnine causes the melanophores to contract. 



An induced current causes the melanophores of normal larvae, 

 of larvae in which the central nervous system has been destroyed, 

 of excised portions of the body and of isolated pieces of skin, to 

 contract. A constant current causes them to expand. 



The melanophores of Ambly stoma larvae do not change their 

 state after the death of the animal, and there is no center for the 

 contraction and expansion of the pigment cells. Nevertheless, the 

 melanophores are under both spinal and sympathetic nerve control 

 as is shown by experiments on larvae the nervous systems of which 

 were variously operated upon. 



