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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Saturday 11th June 2011

I’m not the meticulous type. Maybe I never was or, perhaps, my early interest in set building for amateur dramatics has left its mark. The idea that a bit of rough work wouldn’t be noticed by an audience sitting quite a way away has stayed with me. I tend to vacuum a room so it looks as though it were done yesterday and I always stand back when deciding if I need another coat of paint when I’m decorating.

With gardening, this means I don’t try and remove every single weed from every bed and I don’t want single plants surrounded by finely tilthed soil. And I don’t do annuals.

I simply can’t understand those people who spend weeks growing seeds, pricking them out, potting them on then hardening them off before planting them out for a few weeks of colour before they have to be removed and replaced by some later-flowering species.

Nicotiana sylvestris flowers

My garden is planted with shrubs and perennials that require a minimum of attention year on year. With two exceptions. Most years, I grow Ricinus communis, the castor oil plant, and Nicotiana sylvestris, one of the tobaccos. I’m mostly interested in getting new photos or video of them to update the presentations for my talks and I do like the way the dying Nicotiana flowers do look a bit like a burning cigarette. Since I’ve got a lot of images and video already, I didn’t worry too much when the seeds I’d collected from last year’s Ricinus didn’t work. My Nicotiana seeds, however, did very well and, even with my rough treatment, I ended up with about a dozen plants suitable for planting out.

The worry is that, once the plants are out, the slugs will have a feast and I’ll be left with nothing. So, I use slug pellets. There’s a lot of controversy over the use of slug pellets and most of it is based on three misunderstandings.

People assume that poison works the same way for all creatures so they don’t understand that a poison that kills a slug won’t necessarily kill a bird. They don’t recognise that looks are important in food selection and the blue slug pellets don’t look like food to birds. And, crucially, they don’t understand how poisons work. They’ll say that the problem is not birds eating the slug pellets it is birds eating the slugs that have eaten the slug pellets.

Poisons work by creating chemical reactions in the body of the poisoned. Depletion of essential chemicals in the body may cause the harm, as when oxalates from a plant harvest calcium from the body. Or, the substance formed by the reaction is one that causes damage to the body’s systems.

Either way, the poison gets used in doing the poisoning. If the dose is right. Obviously, if enough of a poison is ingested then there may be insufficient of the substance it reacts with to destroy all the poison. Or, death may occur before all the poison is consumed. That’s why it is essential not to use too many slug pellets. As well as being a waste of money, it is just possible that it could leave unused poison in the dead slugs in sufficient concentration to cause problems for birds.

I don’t know if Dr William Palmer understood this when he killed John Parsons Cook in 1856. Since it took him two attempts it is possible he didn’t. Palmer gave Cook strychnine on two consecutive nights. The first night, Cook was very ill but survived. On the second night, Palmer was successful. Strychnine had only been identified in 1818 and it was some years later before it was isolated so little was known about it. Post mortem examination of Cook’s internal organs failed to identify any strychnine.

It may be that the techniques for testing were inadequate or it may be that Palmer’s interference during the harvesting of Cook’s organs (though suspected already, Palmer was allowed to be present at the post mortem examination) destroyed any remaining strychnine. Or, it is possible that Palmer used just enough strychnine to result in Cook’s death with none left over. Forensic scientists of the time did not understand that you shouldn’t look for the poison itself, you should look for the metabolites, the products of the chemical reactions caused in the body.

We’ll never know if Palmer was expert at selecting the dose of strychnine but it is possible that he learnt from the eleven murders he is believed to have committed before John Parsons Cook.

With poison, as with food, enough really is as good as a feast.