On the Physiological Actions of Plants. 405 



?!k-4. The excellence of the etigravlng— a weTT executed imitatiSn' 

 would require the aid of an able artist ; and as engraving on cop- 

 per and on wood produce these effects by opposite means, if designs 

 from both were used on each note, the difficulty of engaging two 

 eminent artists in such a nefarious trade would enhance the ob- 

 stacles to successful forgery. The tracing on copper by an engine 

 any series of curves, may easily be imitated by what is called en- 

 gine-turning ; but the most perfect specimen of this sort of en- 

 graving is that devised by Mr Perkins. 



" 5. Numbering each note has been adopted by all .banks, and some 

 number them both with impressions from copper and from wood. 

 These have all been successfully imitated ; yet this numbering often 

 has led to the detection of forgery. The numhering-engine, used . 

 by the Bank of Ireland, is tiie most perfect which the author has 

 seen, combining speed with accuracy, and registering its own work 

 with unerring precision. 



*' 6. The signatures of some of the officers of the bank have usu- 

 ally been added to the note, from the known difficulty of exactly 

 imitating a handwriting. 



" 7. Frauds on bills and cheques have been committed by deletion 

 of the common ink in which the amount of the bill has been writ- 

 ten — the substitution of a larger sum. The author recommends 

 the use of an ink, not effaced by chemical agents, without damaging 

 the paper. For this purpose, he conceives that a carbonaceous ink, 

 submitted by him to this Society some time ago, is well suited ; 

 especially when used on the softer kinds of paper, such as that ' 

 made by the engine now used for making paper in one continuous 

 sheet." 



.iit nO S 

 February 3. — Sir T. M. Brisbane, Bart., President, ill the 

 Chair. The follo^ving papers were read : — 



1. Observations on the Influence of various circumstances ,h^';;^ 

 Vegetation in modifying the Physiological Actions- of ^ 

 Plants. By Dr Christison. -■■■% 



" The author commenced witii some remarks on tiie various 

 causes by which the actions of plants and of their products on the 

 animal body may be modified, and on the great vagueness and un- 

 certainty of the information at present possessed in regard to the 

 influence of those causes wiiich seem to arise in peculiar circum- 

 stances of vegetation, more especially climate, weather, soil, and the 

 progress of vegetation. He then stated the soui-ccs of information 

 on these points, namely, the curative or therapeutic action <»f drugs 

 on man, — their effects on the healthy functions both of man and 

 animals, either as medicines or as poisons, — tiieir sensible qualities, 

 — and their ciiemical analysis ; and he assigncjd reasons for discard- 

 ing the first of these from the inquiry, and for trusting, in a gre^t 

 measnre, to tlie eritferions derived from sensible qualities, — fron» 



