308 Canadian Record of Science. 



For stimulation, as in my work on the Terrapin, a Du Bois 

 inductorium, fed by one Daniell's cell, was employed. 



I. Spontaneous Rhythm of the differents Parts of the Heart. 



The subject is so interesting, and such important con- 

 clusions have been drawn regarding it, that I shall give a 

 condensed account of a large number of experiments on 

 this subject. 



Exp. I. — Chelonia imbricata ; caught only twenty-nine hours. 



At 10.25 a.m. a ligature placed around the auriculo-ventricular 

 junction ; ventricle not arrested till ligature is drawn very tight. 



10.28 a.m., 1st beat of ventricle. 



10.30 '■ 



2nd 



10.32 " 



3rd 



10.34 " 



4th 



10.36 " 



5th 



10.38J " 



6th 



The rhythm never got faster, but gradually subsided. 



Exp. II. — Chelonia imbricata. 



At 11.35 a.m. ligature drawn tightly at junction of sinus with 

 auricle ; complete arrest of all parts posterior to the ligature. 



1 p.m. After several pricks with a seeker, a succession of beats 

 but no spontaneous rhythm ; sinus beats regularly from the first. 



2.15 p.m. Ventricle became rigid throughout almost its whole 

 extent. Eight auricle much more vitality than left auricle. 



3.30 p.m. Not possible by mechanical excitation to call forth a 

 beat in left auricle ; right auricle still somewhat excitable- 

 Ex?. III. — Chelonia my das, most lively specimen of any marine 

 turtle I have seen. 



At 12.30 a.m. animal bled freely after destruction of brain. 

 Greater part of auricles proper (" bulged " part) cut away ; they 

 continue to beat in harmony with the sinus and sinus extension 

 (" basal ") or " flattened " portion of Gaskell. 



Soon ventricle cut clearly free from the rest of the heart, i.e.. no 

 sinus extension adhering. Sinus and auricles act together in se- 

 quence and maintain the original rhythm of 32. 



12.45 p.m-12.48 p.m. Ventricle 3 beats. 



12.54 " Ventricle 14 beats in 1 minute. 



12.58 " " 17 



12.58 P.M.-1.02 p.m. Several small groups of beats. 

 1.03 " Ventricle 8 beats in 1 minute, all grouped. 



