Roijal Society of Edinburgh. 65 



ROYAL SOCIETY OF EDINBURGH. 



The first ordinary meeting of the 61st session of the Society was 

 held on Monday the 4th of December at 8 p.m. 



Sir T. Makdougall Brisbane, Bart., President, in the Chair. 

 Professor Christison read a paper having the following title : — " On 

 the Influence of various circumstances in Vegetation upon the Ac- 

 tivity of Plants." Part II. The Umbelliferous Narcotics, of which 

 the following is a summary : — 



In the first part of this inquiry the author gave an account, in 

 1 840, of some observations made by him as to the influence of sea- 

 son on the activity of the acrid plants of the natural family Ranun- 

 culacea, and of the narcotics belonging to the family Drupacece. In 

 the second part now laid before the Society he proceeded to relate a 

 series of experiments instituted by him with the view of determining 

 the influence of season on the activity of the poisonous narcotic 

 plants of the family Umhellifer^. 



The plants belonging to this family are for the most part aromatic 

 and stimulant, and destitute of poisonous properties. In four spe- 

 cies only have narcotic properties been unequivocally recognised, 

 viz. Conium maculatum, (Enanthe crocata, Cicuta virosa and ^thusa 

 Cynapium ; but these are universally held to be highly energetic. 



1. The Conium maculatum, Common Hemlock. No accurate in- 

 formation is yet possessed as to the influence of season on the acti- 

 vity of this species ; for all investigations on the subject are vitiated 

 by the uncertain strength of its preparations, and the ignorance which 

 prevailed till very lately as to the conditions required for securing 

 their uniformity. The author has found by experiment, as Professor 

 Geiger had already been led to conclude, that every part of the plant 

 is poisonous, — the root, the leaves, and the fruit ; and that the root 

 is least active, the leaves much more so, but the fruit most active of 

 all. The root is commonly held to be most active at Midsummer, 

 when the plant is in full vegetation and coming into flower ; but 

 this belief is founded only on a single, and not altogether conclusive 

 experiment made by Professor Orfila. The author found this part 

 of the plant to be so feeble at all times, that its respective energy at 

 dift'erent seasons could not be satisfactorily settled. The expressed 

 juice of twelve ounces of roots had no appreciable eflfect on a small 

 dog at the end of October or towards the close of June ; but an al- 

 coholic extract of six ounces at the beginning of May killed a rabbit 

 in thirty- seven minutes when introduced into the cellular tissue. 

 The leaves are commonly thought to be most energetic when the 

 l)lant is coming into flower at Midsummer, and to be very feeble 

 while it is young. The author finds it to be probable that the leaves 

 are very active at Midsummer; but he has likewise observed, that 

 they are eminently energetic in the young ])lant both at the begin- 

 ning of November and in the month of March, before vegetation 

 starts on the approach of genial weather ; thirty-three grains of a 

 carefully prepared alcoholic extract, representing one ounce and a 

 third of fresh leaves, killed a rabbit in nine minutes when introduced 

 into the cellular tissue. The frnit is most active when it is full-grown, 

 Ann. ^ Mag. N. Hist. Vol. xiii. F 



