xxxvl proceedings of tdk 



Oedinaey Meeting, QtitJanuaky, 1879. 



Alfred T. Brett, Esq., M.D., President, in the Chair. 



Mr. Frederick Littleboy, Hunton Bridge, Watford, was elected a 

 Member of the Society. 



The following lecture was delivered : — 



"Poisons not always Poisons." By Professor John Attfield, 

 Ph.D., F.C.S. (F/r^ep. 147.) 



The President said that Prof Attfiekl's lecture proved the truth of the common 

 saying — " What is one man's meat is another man's poison." This was, however, 

 more applicable to the lower animals than to man. He had often been struck 

 with the deadly action of bruised laurel leaves on insects. The similar action of 

 sulphur, whether applied in the solid form or as snlphurous acid fumes, was also 

 remarkable. He had been told that caustic lime thrown into a pool would destroy 

 any fish that might be in it, but he should have thought that the lime would be 

 too much diluted for the fish to be injured. He did not consider the chalk in the 

 Watford water to be injurious, for our constitution required lime, and we took 

 more of it with our solid food than in water. 



Mr. James Hopkinson said that it had long been known that if sufficient 

 caustic lime were thrown into a pool to render the water perfectly white, the fish 

 would rise to the surface dying or dead. 



Mr. Littleboy stated that he had often eaten a considerable amount of the fruit 

 of the yew, and it had never h-ad any injurious efiect, but he knew that the stone 

 should not be eaten. The fruit of the Irish yew was more luscious than that of 

 the common yew. 



Mr. E. M. Chafer said that there M'as one plant in particular the flowers of 

 which had a poisonous effect upon insects and not upon the higher animals. He 

 alluded to a species of I'yrethruDi, which he believed formed the basis of most of 

 the insect powders. It had occurred to him that as strychnine acted on the 

 nervous system it might not have the same poisonous effect on mites as on more 

 highly organised animals ; and that as sulphate of zinc probably contained a 

 large quantity of combined water, the spider might possibly have existed on the 

 water, rejecting the mineral matter. 



Professor Attfield replied that, with regard to bruised laurel leaves killing 

 insects, the effect was doubtless due to hydrocyanic acid. Laurel leaves probably 

 contained amygdalin, which when brougbt into contact with moisture, as in 

 bruising the leaves, broke up into various compounds, one of which was hydro- 

 cyanic acid. At the same time there were animals, as frogs and toads, which 

 would take a large quantity of this acid without injuiy. With regard to the 

 action of lime on fish, a small quantity of lime throwai into water might be quickly 

 converted into carbonate of lime or chalk, but a large quantity would act as 

 caustic lime, which being a powerful alkali would not only kill, but even dis- 

 integrate animals. It was a well-known tact that Fyrcthrum carneum was an in- 

 secticide, but how it acted was not known. It was also well known that even 

 when given in considerable quantities it did not affect the higher animals, as 

 dogs and cats. Mr. Chafer's suggestion about strychnine might probably indi- 

 cate the truth. Strychnine being a great nerve-paralyser would be a poison to 

 all animals having nerves like man, but to those having a less complete organi- 

 sation he could conceive that it might be a food, for though it resisted the action 

 of hot oil of vitriol, which no other vegetable poison did, it was pretty easily 

 oxidised, and oxidation was the leading feature in the digestion and assimilation 

 of food. With regard to the action of poisons generally, the facts he had brought 

 forward would seem to show that the substances called poisons were only truly 

 poisons when the animals taking such .substances were unaccustomed to them, or 

 when the substances were swallowed in quantities larger than usual. 



Mr. E. M. Chater and Mr. J. AVatson "Walker were appointed 

 auditors of the accounts for 1878. 



