286 ESSAYS AND OBSERVATIONS 



and at twenty minutes before nine in the' 

 morning, I immerfed the whole body of the 

 fjrog in a turbid folution of opium in water, 

 in a fmall bafon, which I covered, to pre- 

 vent the frog from leaping out of it. Thir"' 

 ty Jive minutes after immerfion, I took it out 

 of the folution and opened the thorax and 

 pericardium. The heart's auricle, which 

 was much diftended with blood, beat 15 

 times in a minute, but the heart itfelf, only 

 6 times. Forty minutes paft nine {viz. 

 twenty five minutes after the frog was taken 

 out of the folution oi opium) the heart feem-- 

 ed to have recovered more life j for it per- 

 formed eight pulfations in a minute : the 

 contradlions of the auricle now became 

 feebler, and were fcarce more numerous 

 than thofe of the heart, but always preceeded 

 them fome little time. Six minutes before 

 ten this heart moved only fix times in the 

 minute. Twenty four minutes paft ten it 

 made only five pulfations in fixty five feconds, 

 the firft, third, and fifth of which pulfations 

 were after an interval of fifteen feconds, and 

 the fecond and fourth after a paufe of ten 

 feconds. Seventeen minutes before twelve, 

 and tivo hours and twenty ei^ht minutes after the 



frog 



