REACTIONS OF THE SPOTTED NEWT 197 



so marked as with the 4% solution. No certain reaction was 

 obtained with this solution upon other parts of the body. 



A 1 % solution gave a fairly quick though not violent response 

 in the case of a single animal, used, of course, upon the head. 

 Two other animals slowly withdrew from the stimulation after 

 long delay. The remaining animals gave no response at- all to 

 this solution, which is probably about the limit of dilution for 

 this salt. 



Judging from the comparative reactions of the hydroxides of 

 potassium and sodium it seemed likely that the animals would 

 have reacted to the potassium chloride in the same way as to the 

 sodium salt, so the former was not used. 



It is of course evident that in all of these experiments the 

 solutions are more dilute than is indicated by the time they 

 actually come in contact with the animal, since they must be 

 somewhat diluted by the surrounding water, even though the 

 pipette be held as close to the animal as possible. 



Experiment 6. To test the animals for alkalies solutions of 

 sodium and potassium hydroxides in distilled water were used . 

 The reactions obtained in the two cases were of the same char- 

 acter and, apparently, of the same intensity. The first experi- 

 ments seemed to show a slightly greater sensitiveness to the 

 potassium solutions, but later experiments showed that this 

 was not the case. Since, therefore, the reactions were the same 

 in the two cases, only the experiments with the potassium 

 hydroxide will .be described. Nine animals were used in this 

 experiment. 



A 2% solution of the potassium hydroxide when squirted on 

 the head of an animal caused instant and extremely violent 

 reaction, as though the animal were in great pain. A very small 

 quantity of the solution was sufficient to cause this reaction, and 

 in no other solution of the same strength was the reaction so 

 violent. When this same solution was brought in contact with 

 the body or tail of the animals the reaction was almost as quick 

 and quite as violent as on the head, the animal writhing and 

 biting at the spot stimulated as though in agony. 



A 1% solution gave reactions upon head and body that were 

 nearly as marked as those for the 2% solution, and a .5% solu- 

 tion gave nearly the same reactions for head and body, except 

 that they were slower in starting. 



