206 THEO. C. BURNETT. 



is well known when they are suspended the auricles contract 

 spontaneously. When placed in dilute sea water the rate was 

 always increased by several beats per minute, and they gave an 

 uninterrupted series of contractions gradually diminishing in rate 

 and amplitude, lasting from seven to twenty-eight hours. Usu- 

 ally when longer than twelve to eighteen hours, towards the last 

 the contractions would be irregular, with pauses between groups. 

 Control auricles in "Ringer" showed practically no difference. 

 They too exhibited a slight increase in rate and gave the same 

 characteristic series of contractions — the average being about 

 fourteen hours in both " Ringer" and sea water, with the longest 

 and the shortest records to the credit of the sea water. The fol- 

 lowing description of a few experiments will supply some details. 



Exp. Jan. 28/'o7; temperature ij° C. Strip A was placed 

 in Ringer's solution. During the first four hours no contractions 

 ■occurred. During the next four hours there were four series of 

 rapid contractions, each series lasting from two to five minutes, 

 with one half to one hour between. In ten hours from begin- 

 ning the experiment the strip failed to respond to the induced 

 current. Strip B was placed in dilute sea water. During ten 

 hours it did not give a single contraction. At the end of this 

 time it still responded feebly to the induced current. The auricle 

 of this heart was suspended in dilute sea water and gave a fine 

 series of contractions lasting about three hours. Before immer- 

 sion the rate was sixteen per minute ; after immersion it was 

 eighteen, becoming slower toward the end of the three hours. 

 This was the shortest series of contractions obtained. For some 

 unaccountable reason both the ventricle and auricles gave out in 

 a much shorter time than usual. 



Exp. Feb. i/'oy ; temperature 20 C. Two strips of the 

 ventricle were prepared in the usual way. Strip A was put in 

 Ringer's solution, and after a latent period of twenty-five minutes, 

 gave a single vigorous contraction. It then remained quiet for 

 twenty minutes, when it again began to contract, and gave a 

 series of contractions lasting about ten hours, the rate varying 

 from one to eight per minute. Twenty-two hours after beginning 

 the experiment it was stimulated with the induced current, but 

 gave no response. Strip B in dilute sea water remained perfectly 



