That hemlock is slightly irritant locally is inferrible from the warmth of stomach mentioned by Dr. Earle as produced by it when swallowed, and from the acrid properties of its active principle. There is every reason to believe that it operates on the system, through the absorption of its active principle; as its peculiar effects are produced by conia, to whatever part having the absorbing power it may be applied, and with a rapidity proportionate to the degree of that power in the part. Besides, though Dr. Christison could not detect it in the blood, it was discovered there by Mr. Judd, in animals which had been poisoned with it. (Christison's Dispensatory, Am. ed.,p. 411.)

I have before stated my belief, that the action of hemlock is directly sedative to the nervous centres, and especially those of the brain. Dr. Christison infers, from the occurrence of paralysis of the voluntary muscles, that it operates primarily on the spinal marrow. But it is not the spinal marrow that governs the voluntary movements. its centres are those of reflex action, and not those of volition. it is true that organic injury or disease of the cord produces palsy of the voluntary muscles; but this is by interrupting their communication with the brain by disease of the connecting fibrils, not through disease of the centres. Now it is not probable that conium operates by incapacitating the fibrils for the performance of their conducting function. By paralyzing merely the spinal centres, it could only paralyze their reflex function. The loss of power, therefore, in the voluntary muscles appears to me to result from an impression upon the cerebral centres; upon those, namely, through which the will operates; as the same effect follows apoplectic effusion. A proof that it is the cerebral centres upon which the poison acts is, that the other phenomena are mainly cerebral, such as vertigo, dimness or loss of vision, headache, etc., not to speak of the delirium and stupor which are asserted by many, and have generally been believed to be produced by the poisonous action of hemlock. That these latter phenomena should not have been observed in all instances, is no proof that those persons have been mistaken who have noticed and recorded them. it is not impossible that the influence of the poison may, on one occasion, be exerted specially on the proper sensorial centres, and, on another, upon those of voluntary motion; and that, in other instances, again, it may affect both. Chloroform exhibits the same diversity, being directed sometimes with peculiar energy to the sensorial centres, and at others to the centres which govern the actions of the heart. On the whole, therefore, I think we are safe in considering conium as a cerebral sedative, extending its influence, in fatal cases, to the respiratory centres, and causing death by asphyxia.

* In the Liverpool Medico-chirurgical Journal for July, 1858, Dr. T. Skinner gives an account of the poisonous effects of hemlock, drawn from the observation of five cases of children from five to eight years of age. The symptoms were dryness of the fauces, a feeling of constriction of the pharynx, slight headache in a few instances, disordered vision, dilated pupils, drowsiness, livid face, circulation and respiration depressed, coldness of the surface, and paralysis first of the voluntary and afterwards of the involuntary muscles, those of respiration being the last to fail. On the occurrence of paralysis there was more or less coma, with foaming at the mouth, and death appeared to take place through the coma. Dr. Skinner noticed no violent delirium, intoxication, or convulsions. I think these symptoms fully sustain the view taken in the text that conium is a cerebral sedative. (Note to the second edition.)