CHEMICAL AGENTS ON CHROMATOPHORES 177 



Pouchet (76) observed that curara did not modify the reac- 

 tion of the pigment cells of turbot, viz., the pigment cells re- 

 mained in an expanded condition. Lode ('90) has found that 

 subcutaneous injection of a mixture of curara and glycerine 

 caused a dark coloration in the adult trout (Salmo fario). He 

 ligated the aorta and found that in the anterior end with the 

 intact circulation expansion of the pigment cells occurred, while 

 in the posterior end with the interrupted circulation, the pig- 

 ment cells remained contracted. These experiments are not 

 conclusive because the removal of the circulation interfered 

 with normal metabolism of the cells. Moreover, the pigment 

 cells are very sensitive to the changes in their oxygen supply. 

 He observed that if the spinal cord of a curarized trout was 

 stimulated, no contraction of the pigment cells occurred. If the 

 pigment cells were stimulated directly, the pigment cells con- 

 tracted. He concluded that the curara destroyed the nerve 

 endings but did not affect the pigment cells. Laurens ('15) 

 found that if Amblystoma larvae were placed in a 0.2 per cent 

 solution of curara their movements were abolished and the 

 pigment cells remained expanded under all conditions. He con- 

 cluded that this failure on the part of the pigment cells to react 

 was probably due to the direct effect of the solution on the ani- 

 mal; or asphyxiation of the larvae by the curara, and the con- 

 sequent increased amount of CO2 in the blood may have caused 

 the melanophores to remain expanded. If a small amount of 1 

 per cent solution of curara was injected into the body cavity the 

 larvae were rendered unmotile but the melanophores reacted to 

 light (expanded) and to darkness (contracted) as usual. He 

 concluded here that this experiment did not prove that curara 

 had no effect on the melanophores, for it has been shown that 

 melanophores will contract and expand after all nervous con- 

 nections have been destroyed. 



Carlson ('06) has shown that in weak solutions of curara there 

 was a primary stimulation of the heart ganglion of Limulus. It 

 had a little effect on the heart muscle. Young ('81) observed 

 that in Mya (sp.) and Solen (sp.) there was a distinct accelera- 

 tion in the number of heart beats, and sometimes a diminution, 



