182 



T- u , I Time between two con- x- u . « 



Tune between two con- fractions of two adjacent ^'"^^ betweeen two con- 



tractions of control. 



fragments. 



tractions of the other. 



Greatest difference before separation, 1.0 

 Average difference before separation, 0.2 



34.6 

 5.9 



Greatest difference after separation, 1.0 

 Average difference after separation, 0.0 



1.0 

 0.1 



The interpretation of this phenomenon is rather dilficuU. 

 The irrigularity of the contraction after the new growlli 

 of the two fragments had intermingled could possibly be 

 explained as a mechanical effect. 



In other experiments, the distances between the two frag- 

 ments were not so great. The result was. that only after 

 18 — 72 hours incubation, the two fragmina pulsated as one. 

 The space between the two fragments could after 48 hours 

 incubation scarcely be seen and a perfect simultaneous pul- 

 sation was obtained. A tj'pe of such an experiment can be 

 seen in table 20. In these experiments where the distances be- 

 tween the two adjacent fragments are rather great, it takes 

 a relatively long time before the respective pulsation be- 

 comes synchronous. This experiment rej)resents also the 

 group, where svnchronic contraction was obtained with two 

 fragments of heart derived from two different chicken em- 

 bryos. 



