398 Prof. Christison on the Poisonous Properties of Hemlock, 



been supposed to extinguish sensation, merely because, by indu- 

 cing general paralysis, it takes away the power of expression. 

 At least, in some experiments I have made, sensation did not ap- 

 pear to be affected ; and the whole phenomena were identical 

 with those produced by conia, In these experiments I used very 

 strong extracts prepared by absolute alcohol from the fresh leaves, 

 or the full-grown seeds ; and each of them occasioned, in doses 

 of thirty grains or thereabouts, paralysis of the voluntary muscles, 

 with occasional slight convulsions, then paralysis of the respiratory 

 muscles of the chest and abdomen ; and finally cessation of the 

 action of the diaphragm ; sensation appeared to continue so long 

 as it was practicable to make an observation on the subject ; and 

 the heart contracted vigorously for a long time after death. 

 From these extracts a very powerful odour of conia was disen- 

 gaged by caustic potassa. 



It seems to me clear, therefore, that the action of conia and of 

 hemlock are identical, or nearly so ; and that conia is either the 

 active principle of the plant, or contains it in a modified form. 



I wish I could have added to these observations on the poison- 

 ous effects of conia and hemlock, some account of their physiolo- 

 gical properties in small doses. This branch of the inquiry into 

 their action I have not yet been able to investigate. It cannot 

 be pursued with any accuracy by experiments on the lower ani- 

 mals. The phenomena must be ascertained in the human sub- 

 ject chiefly, which I have not hitherto been able to accomplish. 

 On this head it may merely be observed, that, if physicians or 

 physiologists would acquire definite information as to the phy- 

 siological effects of hemlock in small or medicinal doses, they 

 must begin the inquiry anew. Little importance can be attached 

 to any thing already done in this field, as I have no doubt what- 

 ever, that by far the greater proportion of the preparations of 

 hemlock hitherto employed have been of very little energy, and 

 in the doses commonly used are absolutely inert. 



