CHEMICAL AGENTS ON CHROMATOPHORES 163 



The fish live longer in sodium solutions, and the pigment cells 

 retained their irritability longer. The pigment cells expand if 

 transferred after they are contracted in potassium salts. Is 

 this reaction specific for the sodium ion or is it due to the in- 

 creased number of undissociated molecules in sodium solution? 

 It cannot be positively concluded whether this difference in 

 residual molecules is enough to account for the difference in the 

 rate of contraction of the melanophores in sodium and potas- 

 sium salt solutions. The ascribing of the principles of salt ac- 

 tion to the anion or cation without the consideration of the 

 residual undissociated molecule is just as out of proportion in 

 the field of physiology as to say that the undissociated alkaloids 

 and other substances have no action. 



Reactions to alcohols 



Whether or not alcohols have a stimulating action is a much 

 debated question. The Schmiedeberg school of pharmatiblo- 

 gists maintains that alcohols produce no primary stimulation of 

 the central nervous system. According to this view the giving 

 alcohol to a mammal, if followed by an increased muscular ac- 

 tivity, is said to be due to the depression of the cerebral centers, 

 thus removing the restraint from the motor areas. Binz and 

 his followers hold to the view that alcohol first stimulates and 

 then depresses the nerve cells. 



The literature on the pharmacological action of alcohol on the 

 heart and other tissues is very extensive, but to my knowledge 

 there are no records of any attempts to determine its action on 

 the melanophores. Whatever action the alcohols exert on the 

 melanophores will not settle the question whether alcohols 

 stimulate or depress the nervous system, as the melanophores in 

 the very nature of their origin and structure must be looked upon 

 as specialized mesenchymal cells. While it is not at all improb- 

 able that the general facts observed with melanophores may be 



1 After these experiments were completed Spaeth 1916 published results, 

 where he subjected isolated scales of Fundulus to vapors of alcohol, ether and 

 chloroform and always obtained a contraction of the melanophores, and larger 

 amounts of these vapors inhibited the contraction. 



