EFFECT OF ADRENIN UPON RATE OF LOCOMOTION. l6l 



normal rate was 53.4 seconds; but after one day in adrenin solu- 

 tion (i : 15,000) the average time needed to travel the same 

 distance was increased to 69.5 seconds. Furthermore, as an 

 indication that the change was in response to a definite stimula- 

 tion, and not merely the expression of a generally weakened 

 physiological condition, such as does occur after a time -when 

 the animals are kept in the laboratory, there was a decided 

 improvement after the animals had been placed in water again 

 for two days. The rate this time was even better than the 

 original, 51 seconds. 



This same retarding influence of adrenin, followed by recovery 

 in water was found in the next five planarians tested. But the 

 third Series, as is shown in Table I., gave apparently very dis- 

 appointing results. It may be interesting, however, to note 

 that the animals of Groups B and C which gave good initial 

 rates had been tested before with adrenin. The very poor rates, 

 therefore, of the planarians of Groups A and D, which had been 

 kept for some time in the laboratory, and had not been previously 

 used, indicate that these animals were no longer in the same 

 condition as those of the first experiments and might well be 

 affected differently by the same extract. 



Fresh planarians. were then obtained and the same tests re- 

 peated. The results of these, also recorded in Table I., seem to 

 confirm the conclusion drawn from the first experiments, that 

 adrenin produces a decrease in the normal rate of locomotion of 

 Planaria, which is overcome when the animals are again placed 

 in water. 



The nature of the effect of adrenin upon the muscular con- 

 traction of Planaria is not, however, as simple as the decrease 

 in the rate of locomotion would indicate. Observation of the 

 animals reveals clearly that the effect is not merely one of 

 weakened muscular response to mechanical and contact stimuli. 

 There seems to be no delay in the time of reaction to stimulation, 

 and no constant decrease in the strength of the contraction. It is 

 moreover, apparently not the same effect as that which Moore (5) 

 found produced by strychnine, as no reversal of the normal 

 response to stimulation was observed at any time after treatment 

 with adrenin. Experimental animals, touched with a camel's 



