EXPERIMENTS ON MEDUSsE 



27 



killed the animals in order to preserve them. In 

 other experiments, the two animals did not heal 

 together so completely. It happened in the case 

 where the animals had grown 

 together most completely, as 

 represented in Figure 5, that 

 they contracted synchronically 

 like one animal two days after 

 the operation. The animals, 

 on the other hand, that had not 

 grown together to such an ex- 

 tent did not contract synchro- 

 nically. I believe that if one 

 could succeed in healing two 

 hearts together completely, 

 they would also beat synchro- 

 nically. 



The assumption of a " centre 

 of coordination " situated in 

 the ganglia of the margin of a 

 Medusa thus becomes un- 

 necessary. In the frog's heart, 



the sinus venosus beats faster than the auricle, ven- 

 tricle, and bulbus aortae. Hence, each contraction of 

 the sinus venosus acts as a stimulus, which causes a 

 contraction of the auricles, and the contraction of the 

 latter is the stimulus which causes the contraction of 

 the ventricle and bulbus aortae. It would follow from 

 this that if we could cause the bulbus aortae in the 

 frog's heart to beat as fast as the sinus venosus we 



FIG. 5. 



-o 



DR. HARGITT'S EX- 

 PERIMENT. 



Two Gonionemi grafted to- 

 gether. Two days after the 

 operation synchronous con- 

 tractions of both animals 

 were observed. 



