322 ESSAYS anp OBSERVATIONS 
“more: However, in four or five minutes, 
it began to beat of its own accord, and, 
at twenty-eight minutes after ten, per- 
formed 19 pulfations in a minute. Thir- 
ty-five minutes paft ten, it beat r2 times in 
a minute. 
15. TWENTY-three minutes paft twelve, 
I cut out the heart of another frog, and 
put it in fountain-water. After twelve 
minutes immerfion, I took it out of the 
water, when it beat above 20 times in a 
minute. Having put it in the water’ for 
five minutes more, it ceafed from motion, 
and, when taken out, did not move except 
when pricked, and then only performed 
one pulfation. 
16, EIGHT minutes paft eleven, I cut 
out the heart of a third frog, and put it 
into fountain-water. Eleven minutes af- 
terimmerfion, its heart beat 8 times in the 
minute, and, four minutes after this, it vi- 
brated 11 times in ‘thirty feconds ; but 
the motion was confined to about one 
third part of the heart next its apex. 
Twenty minutes after immerfion, it con- 
tinned to move much in the fame way ; 
but 
