REACTIONS OF THE SPOTTED NEWT 201 



stimulated. Of these four three reacted in a very slow uncertain 

 way, while the fourth responded fairly promptly. 



The only animal that responded at all to i% alcohol was the 

 one just mentioned as responding fairly quickly to the 2% 

 grade; 1% is, therefore, probably the minimum percentage of 

 ethyl alcohol that will cause reaction in these animals. 



Experiment 9. The effect of cocaine was tried both to see 

 what the effect might be, and to try to distinguish between the 

 sense of taste and that of smell. 



Thinking that the soft moist skin of Diemyctylus would be at 

 least as sensitive to cocaine as the harsh skin of the dogfish that 

 Sheldon used, a 2% solution was first tried. This concentration 

 was found by Sheldon to produce insensibility first to touch and 

 later to chemical stimulation. The cocaine was first tried by 

 painting it over the nasal region of animals that had been taken 

 from the water and allowed to dry for a few moments. In this 

 process it was almost certain that the cocaine must have entered 

 the nasal chamber through the nostrils. After a few minutes 

 the animals were replaced in the water and were tested with a 

 1% solution of acetic acid, such as has been mentioned in pre- 

 ceding experiments, every ten minutes or more during several 

 hours. The cocaine had no apparent effect whatever. 



Thinking that possibly the sensitiveness of the head, after the 

 nasal region had been treated with cocaine, might be due to 

 stimulation of the eyes or the lips by the acetic acid, in spite 

 of the care that was exercised to direct the stream from the 

 pipette in such a direction that it should stimulate only the 

 region that had been painted with the cocaine, the experiment 

 was tried of painting the entire head, dorsal and ventral, includ- 

 ing the eyes, with the 2% cocaine. The result was the same as 

 before. 



In other animals the cocaine of the same strength was used 

 upon the tail; about half an inch of the tail, just caudad to the 

 posterior appendages, was painted entirely round the animal and 

 including the cloaca. This region was tested with the 1% Acetic 

 acid every fifteen minutes for several hours, but no change 

 in its sensitiveness could be detected. 



Another series of experiments in which a 5 % solution of cocaine 

 was used in the same way that the 1% had been used gave 

 no difference in reaction to the 1% acetic acid. A 10% solu- 



