THE NERVOUS SYSTEM OF AMPHIBIA 195 



although during the first ten minutes of the experiment the 

 embryos in distilled water manifested as much disturbance as did 

 those in HCl n/4000, and at times apparently more. Thirty 

 minutes after the beginning of the experiment the embryos that 

 were immersed in HCl n/3000 showed the greatest activity; 

 those in distilled water were slightly active; those in HCl n/4000 

 were perfectly quiet. It was observed throughout the experiment 

 that the movements of the embryos in the acid solutions were 

 of a more convulsive nature than were the movements of those 

 in distilled water. Two hours and five minutes after the begin- 

 ning of the experiment the embryos in HCl n/3000 were still the 

 most active; those in HCl n/2000 were totally inactive; those in 

 HCl n/4000 and in distilled water were slightly active. During 

 the whole experiment up to this point no movements had been 

 observed among the embryos in the cistern water. At the expira- 

 tion of four hours and twenty-five minutes after the immersion 

 in the solutions, the specimens in HCl n/3000 and those in HCl 

 n/4000 were more active than those in distilled water. An hour 

 later the embryos in HCl n/4000 were still more active than those 

 in distilled water. 



During the progress of this experiment it became obvious 

 that at least not all the reactions that were occurring in the var- 

 ious acid solutions could be regarded as due to a normal process 

 of stimulation, for within three hours after the beginning of 

 the experiment the four specimens that were immersed in HCl 

 n/2000 showed marked shriveling of the margins of the fins and 

 the skin had become pale. Upon the discovery of this destructive 

 action, these four specimens were removed and two others intro- 

 duced into the identical solution. These became completely 

 inert to ordinary means of tactile stimulation within forty-five 

 minutes after immersion in the solution. Further observations 

 showed that the specimens that were immersed in HCl n/3000 for 

 four hours had undergone various degrees of decline in irritability 

 to tactile stimulation, and that one had wholly lost the power 

 of response to such stimulation. Prolonged immersion in HCl 

 n/4000 also proved to have a very perceptible injurious effect upon 

 the skin of the embryos. 



