ELEMENTS OF MATERIA MEDICA.

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(b.) The other effects of opium appear, for the most part, to be secondary:they arise out of the nervous lesions just referred to.

4. Opium acts on the Nervous System as an Alterative.-throe kinds of changes, compatible with life, which medicines canin the vital actions of an organ,—viz. an increase, a diminution?alteration of activity. A change in the intensity or energy mere j a -vital actions of the nervous system, would not give a satisfactorynation of the effects of opium. We are obliged, therefore, to ^ eaJ itthat opium changes the quality of the actions. This is what i sby the term alterative.

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The inquiry into the nature and kind of influence exercised by °P lU n e SW'system, presents an extensive field for speculation and hypothesis. . a utb° rlt q

Med. Facv.lt. lib. viii.) declared opium to be cold in the fourth degree, and ms jerk 1 ' 1 ’long prevailed in the schools. It was first opposed by the iatro-chemists. " bo"'

opium to be of a hot nature, (Wedelius, Opiologia, cap. vi. p. 26, 1682). jd p#f”

ever, adopted a middle course, and asserted that it possessed both hot antides (see Crumpe, op. supra cit. p. 91). The iatro-mechanists endeavoured () tli£ pthe operation of opium on mechanical principles. By some expansion, ^ p pert |CScondensation of the blood, was supposed to be produced by the mechanic® P qyalk 8 ’of the opiate particles acting on the nerves (see an account of these opinions t0 b e *Usus Opii, Sect. 1, 1757). Dr. Cullen {Mat. Med. ii. 225) considered <>P ,U an j in 1sedative, and referred its effects to its power of “ diminishing the mobility?certain manner suspending the motion, of the nervous fluid.” Several la e e( lati ,e 'Barbier (Traite Elem. de Mat. Med. ii. 2" de ed.) for example, also call opium foetBrown (Elementa Medicines) declared it to be a stimulant, and his opinion j.jjub-h.adopted by Crumpe {op. supra cit.), Murray ( Syst. of Mat. Med. and Therap■and Dr. A. T. Thomson (Elem. of Mat. Med. and Therap.) in this tb e ° r j

course by the continental Brunonians , as well as by the partisans of theof contra-stimulus. (See some remarks on the modus operandi of opium by Vf 0 ! ein Land. Med. and Phys. Journ. vols. vii. viii. and ix.) Fontana (Treat, on ^ jyof the Viper, iii. 199) ascribed the operation of opium to changes which it in u i a nt a11blood. Mayer (quoted by Orfila, Toxicol. Gen.) declared opium to be botbjstin^

sedative,—viz. stimulant to the nerves and vascular system, but sedative to y 1 ^ s tri>pband digestive organs. Lastly, Orfila (Ibid.) asserts that “ opium, employ e ^ pec"^,doses, ought not to be ranked among the narcotics or the stimulants; it e * er jf nI1 ,eiit e,|, .i

mode of action which cannot be designated by any of the terms at thisployed in the Materia Medica.” These examples, selected out of many °P| n j I b^be sufficient to prove how little is really known of the real action of opium ’ co nfes 5l ° Blieve we shall save ourselves much time and useless speculation by at onceour ignorance on this point. ,

5. The operation of opium, compared with that of other cere ^ r °^ r isti (S 'or narcotics, is distinguished by both positive and negative char aC ’ g aff

The symptoms whose presence constitute the positive c ^* araC i ,] e eprelaxation or paralysis of the contractile tissues, a tendency t° b jj oS estupor, a contracted pupil, and constipation. The sympt° in ®absence furnish the negative characters are tetanic convulsion, aor inebriation, dilated pupil, syncope, gastro-intestinal irritati >topical numbness. ^ ^ e ii>

These are the general characteristics of the opiate medication. To som e _

occasional or perhaps frequent exceptions exist. §51)? ^ e L e s

I have already pointed out the distinguishing effects of hyoscyamus (p-,• jj|J<roi s “J,donna and stramonium (p. 856). The topical numbness caused by aconite ui» ^

its operation from that of opium. Moreover, in three cases of poisoning L, V j

stance, which came under my notice, there was no stupor. Tobacco a 11 {ptes 111 ^,enfeeble the vascular system, causing syncope ; and they also produce S astr . 0 j c |) \> e U jirritation. Furthermore they have not that tendency to induce sleep '' ce , i l \,serve after the use of opium. The speedy operation, short period of inn ^ a c>usually, the presence of convulsions, distinguish the operation of hydro 0 ?