186 JOHN N. LOWE 



18. Cocaine has a primary vStimulating action on the pigment 

 cells of trout. This action is probably on the nerve endings of 

 the pigment cells that connect them with the reflex center. 



19. Veratrine causes a primary contraction of the pigment 

 cells which is followed by a rapid depression (expansion). The 

 action of veratrine is through the reflex center of the spinal 

 cord and medulla rather than local. 



20. Quinine exhibits no primary stimulating action on the 

 pigment cells. The drug has no selective action on tissues, 

 therefore it is a general 'protoplasmic poison.' 



