REACTIONS OF THE SPOTTED NEWT 199 



nostrils and mouth will be discussed later. By directing the jet 

 caudad the eyes could be stimulated with probably but little 

 stimulation of the nostrils and mouth; no certain difference in 

 reaction could be determined from what was seen when the jet 

 was directed in the other direction as noted above. 



A 10% solution of glacial acetic acid was first used, and this 

 was gradually diluted until no reaction was obtained ; this dilu- 

 tion was made in all cases with distilled water. Twelve animals 

 were used, the experiments extending over several days. The 

 water was changed after each set of experiments. 



The 10% solution, as might be expected, caused violent and 

 almost instantaneous reaction when squirted upon the head, 

 while upon the body it caused active though much less violent 

 responses. 



A 3% solution caused fairly quick reaction upon the body, 

 and much more violent reaction upon the head, often a violent 

 shaking of the head taking place. This dilution of the acid is 

 distinctly sour but not irritating to the human tongue. 



A i% solution on the head caused a quick though less violent 

 reaction than in the preceding. Upon the body it caused slow 

 reactions, and in none of the dilutions lower than this one was 

 there any certain response. It will be noticed how much more 

 sensitive the animals are to weak solutions of alkalies than to 

 weak acids. The i% acetic acid has a faintly sour taste. 



A .3% caused a moderately quick response upon the head, but, 

 as was said above, no certain response upon the other parts of 

 the animal. A finger moistened with this dilution of acid and 

 touched to the human cornea caused a brief but decided stinging 

 sensation. 



A .075% solution caused in every animal a moderately prompt 

 and decided response when squirted upon the head. When 

 squirted upon the human tongue it causes a barely discernible 

 sour taste, and in the human eye causes scarcely more sensation 

 than would a drop of cold distilled water. 



A .0375% solution caused a fairly quick and decided response 

 in all animals, in a few cases with a shaking of the head in the 

 manner characteristic of a disagreeable sensation. 



A .01875% solution produced in all animals a negative response, 

 generally fairly quick, and sometimes quite violent. This solu- 



