646 RAYMOND PEAHL. 



The following substances woie used in tlie experiments 



/'Nitric 

 Mineral acids . ^ Hydrochloric 

 I Sulphuric 



Organic acids . - Citric 



Oxalic 

 , Citr 

 IFor; 



Alkalies 



■mic 



fSodium hydrate 

 I Sodium carbonate 



c, I, ,^ ,1 fCopper sulphate 



Salts 01 heavy metals- „• i i 



[Aiuc sulphate 



Other salts 



Cane-sugar. 

 Distilled water 



Sodium chloride 

 Sodium bromide 

 Potassium chloride 

 Mao'iiesium chloride 



Since distilled water was found to have a decided effect in 

 producing a reaction, the solutions were prepared in both 

 distilled water and in filtered tap water. In case of any 

 doubt; as with very dilute solutions, the effects of the solu- 

 tions prepared in each sort of water were tested and 

 compared. 



Since only qualitative results were desired, and for the 

 practical reason of greater convenience, percentage rather 

 than molecular solutions were used. 



/3. Results. — The results are, in a way, so remarkable that 

 they will be presented in some detail. 



Mineral Acids. 



Nitric (sp. gr. 1'42), I pur cent. — Tiiis solution causes 

 strong negative reaction. If a])))lied to the head region the 

 animal turns away from the side stinudated immediately, and 

 strongly. If the stimulus is long continued the animal 

 writhes and twists about violently. 



Stimulation of the posterior region causes the part where 



