is produced by certain vegetable Pouotis. 93 



spine, abdomen, and tail alternately relaxed and contracted, 

 so as to tnrn the whole animal from one side to the other. 

 I have observed, in other instances, spasmodic actions of 

 the muscles, where the circulation was kept up by ariificial 

 respiration, alter the removal oF the head, but not at all to 

 be compared, either in strength or fre<|uency, vvith those 

 vhich took place on this occasion. 1 made pressure on 

 the abdominal aorta for more than a minute, so as to ol)- 

 struct the circulation of the blood in the lower extrennties; 

 but the muscular contractions were not lessened in conse- 

 quence. Half an hour after the injection of the ijiiusion, 

 the artificial res^piration was discontmued. The heart con- 

 tinued to act, cu'culating dark-coloured blood ; the muscu- 

 lar contractions continued, but gradually diminished in 

 strengili and frequency. I tied a ligature round the vessels 

 at the baseot the heart, so as to stop the circulation; never- 

 theless the muscular contractions still continqed, though 

 less frequent and forcible than before, and some minutes 

 elapsed before they entirely ceased. 



In this experiment, the disposition to contraction in the 

 muscles wa» very nuich increased, instead of being dimi- 

 nished, as in those just related. If the infusion of tobacco 

 influences the heart from being absorbed into the blood, and 

 thus coming into actual contact with its fibres, there is no 

 evident reason why the removal of the brain, and the em- 

 ployment of artificial respiration, should occa^^ion so ma- 

 terial a difllrence in its efi'ects. If the contractions of the 

 voluntary muscles had depended on the infusion circulalinc 

 with the blood, it is reasonable to suppose that the pressure 

 on the aorta v^ould have occasioned some diminution of 

 them, and that the complete obstruction of the circulation 

 would have caused them to cease altogether. 



From these considerations, I am induced, on tbe whole, 

 to believe that tbe iniusion of tobacco, when injected into 

 the intestines, influences the heart through the medium of 

 the nervous system ; but I have not been able to devise any 

 experiment, by which tbe truth or fallacy of this opinion 

 might be put beyond the reach of doubt. 



It ai)pears rcmaikabic, that tbe brain and nervous syste'n, 

 although not necessary to the action of the heart, should, 

 when under the influence of the infusion of tob.icc!>, be 

 capable of influencing this organ so as to sto[) its action; 

 but this is analogous to what we see occur in consequence 

 of violent emotions of the mind. Those states of the 

 nervous system, which accompany the passions of j'>y, !car, 



or 



