The Heart of the Sea- Turtle. 309 



1.09 p.m.- Ventricle a rhythm of 7 beats 1 minute. 



1.10 " " 7 



1.11 " " 5 



1.13 " " 16 



1.14 "' " 11 



1.15 " •' 12 

 1.20 " " 12 

 1.25 " " 8 

 1.30 " " 8 



2.25 " " 4-6 and irregular. 



N.B 2.50 p.m. After a previous pause of several minutes. 



rhythm began again, at first, only at the edges of the ven- 

 tricles, then grows gradually stronger and spreads over 

 more of the ventricle, but never involves the whole of it. 



The last observation is important, as it shows how con- 

 traction of certain fibres of the ventricle tend to call into 

 action others, and strengthen those already acting, but 

 weak. Similar cases have been reported for the Terrapin. 



The above cited experiment furnishes the best-marked 

 case of spontaneous rhythm I have met. 



Exp. IV. — Chelonia caretta, about 3 feet long; out of water two 

 days. 



1.05 p.m. Ligature between sinus and auricle and sinus extension 

 does not arrest rhythm of auricles and ventricle, till it is draicn very 

 tight. 



No spontaneous rhythm of any part posterior to the ligature. 



N.B. — 1.30 p.m. On attempting to get the ventricle to pulsate in 

 response to a prick from a seeker, it passes into fibrillar action. This 

 case presents a great contrast to the previous one, but the animal 

 in the latter case had been out of the water two days, while the 

 other specimen was quite fresh. 



Exp. V. — Chelonia mydas. 



11.10 a.m. Ligatured between ventricle and parts just above ; 

 former arrested at once. 



12.10 p.m. Ventricle a beat now and then, on an average I in the 

 minute, auricles and sinus a rhythm of 30. 



1.10 p.m. Ventricle 5 beats in 3 minutes at irregular intervals. 



1.50 p.m. Ventricles 3 beats in 4 minutes. 



2.50 p.m. Auricles irregular ; right beats before left ; ventricle 5 

 beats in 5 minutes. 



4 p.m. Ventricle has almost ceased to pulsate, but a touch of the 



