1 66 E. LUCILE MOORE. 



With a less concentrated solution of adrenalin chloride, I : 

 10,000, the same effect was produced. At the end of an hour 

 the animals appeared dead ; but after another hour in water, the 

 paralyzing effect wore off and the% became very active, but 

 unable to keep up any sustained swimming movements. Kept 

 in water for several days, however, the animals, with one excep- 

 tion, completely recovered, and traveled once more at their 

 normal rate. Adrenin, therefore, seems to have an effect upon 

 larval vertebrate muscle as well as upon the simpler muscle of 

 planarians. 



This work was carried out under the direction of Dr. Florence 

 Peebles, to whom I wish now to express my sincere appreciation. 



SUMMARY. 



1. There is a decrease in the rate of locomotion of planarians 

 after treatment with solutions of adrenin, followed by a return 

 to the normal rate when the animals are again placed in water. 



2. In those individuals which have not been subjected to the 

 influence of the extract more than an hour, this decrease in the 

 rate of locomotion seems to be due rather to an increased excita- 

 bility and lack of coordinated movement than to a slowing of the 

 rate of muscular contraction. 



3. Planarians exposed to the action of adrenin for a longer 

 period do not give evidence of extreme excitability, but seem 

 to show a real decline in activity, which may be a secondary 

 effect following the initial excitation. 



4. Those planarians whose initial rate indicates a state of 

 depression travel more rapidly after treatment with adrenin. 

 This would seem to confirm the suggestion that the effect of 

 this extract upon planarian muscle. is predominantly excitatory. 



5. Although no definite statement can be made concerning 

 the effects of adrenal extract upon the muscular contraction of 

 toad larvae, the indications are that they are similar to the 

 effects produced upon the muscular activity of planarians, and 

 that this effect increases with the age of the individuals. 



