32 MARY DRUSILLA FLATHER. 



continuing until a practically normal rate of pulsation was re- 

 stored. However, the effect was not lasting. Observations 

 made fifteen minutes later showed a rate of 50 for the anterior, 

 and 42 for the posterior vacuole. 



Table II. gives a detailed record of the reaction to adrenalin- 

 1-200,000 solution, in two individuals. From these results and 



TABLE II. 



EFFECT OF ADRENALIN, i : 200,000. 



many other similar ones it seems probable that adrenalin of the 

 above strength has a specific quickening effect upon the contrac- 

 tile vacuole. This effect is usually of very short duration, 

 especially if it produces an abnormally rapid rate of pulsation. 



Treatment' with adrenalin, 1200,000 solution, produces also 

 a marked dilation of the vacuoles which persists for some time 

 after the rate of contraction has returned to normal. From 

 several records there are indications that the duration of the 

 pulse acceleration is prolonged by increase in the strength of tin- 

 solution up to a certain point which has not been exactly deter- 

 mined. In three individuals one drop ot adrenalin, i- 10,000 

 solution proved fatal. Not enough records with intermediate 

 strengths have been taken to warrant any definite .i^Mimplum 

 of a specific optimum strength. 



It is evident from the re-cords in Table III. th.it tin- effects 



