EARLY PULSATIONS OF LYIMPH HEARTS 387 



at once, and, with them, the pulsations of the lymph heart in 

 chicks of this stage. 



In chicks of seven to seven and one-half days (measuring 22 

 to 24 mm.) our records show practically the same connection 

 between the beating of the lymph heart and the body movements. 

 The l3rmph heart beat from three to nine times during each 

 periodic spasm and never in the intervals of rest. But, at this 

 stage, strong Ijonph heart contractions were accompanied at 

 times by feeble tail movements and occasionally they were 

 dissociated altogether from contractions of the tail. 



Stage 2. Our observations of chicks of eight days showed that, 

 on the average, 5.3 beats of the lymph heart accompanied each 

 periodic spasm but that the majority of these beats were dis- 

 coordinated from the tail movements. In addition, an occa- 

 sional single pulsation of the lymph heart occurred in the period 

 between spasms, with no accompanying body movement. In- 

 jections of the lymph heart at this and later stages, show it to 

 possess the form of a definite oval sac. 



One embryo of this stage (7 days, 21^ hours, measuring 24.5 

 mm.) was kept under continuous observation for four hours, 

 and showed an interesting reaction to the treatment with chlore- 

 tone. The chick was first observed for an hour and a half. We 

 found that an average of 5.3 lymph heart beats accompanied 

 each spasm and that, occasionally, an independent lymph heart 

 contraction occurred in the period of rest. Chloretone (1:4000 

 in warm Ringer's solution) was then dropped on the embryo. 

 The body movements and lymph heart beats both ceased for a 

 few minutes. Then the lymph heart began to beat, an average 

 of 4.7 times in every minute, with no accompanying body move- 

 ments whatever. This beating of the lymph heart continued 

 for forty minutes before the effect of the chloretone wore off. 

 With the elimination of the body movements, the lymph heart 

 pulsations occmTed singly, instead of in groups, and they lost 

 all semblance of periodicity. 



Finally, after about fifty minutes, the body movements began 

 to recur, gradually regaining their former periodicity. With the 

 return. of the body movements, the Ijanph heart regained its 



