To those people who are interested in writting a novel or a fiction story. I found a very interesting book with information about poisons and everything it envolves it. It could be very useful for the plot of the story.

Poisoning is a serious business. Once the preferred method of murder, homicidal poisoning has somewhat fallen in popularity because modern pathologists can detect almost any poison. Of course, the pathologist must know which poison to test for. There are, in fact, very few poisons that are ideal - odorless, colorless, tasteless, quick acting, and nontraceable. Many poisons meet one, two, even three of the criteria; many drugs have their own built-in clues for the detective.

Definition of Poison.- What is a poison? We can define poison as "a substance that through its chemical action usually kills, injures, or impairs an organism" or "a substance that inhibits the activity of another substance or the course of a reaction or process." Anything in a large enough dose can prove toxic. Our concern is feasibly deadly doses.
If death by poison is involved, the writer owes the reader a respect for the reader's intelligence. All too aften, a writer loses credibility by creating a world very similar to the real one, then shattering it by using an incorrect fact. Poisons are a time-honored part of mystery fiction. Yet, too often a writer will have a victim swallow something and collapse, dying instantly, when in real life the poison would have taken at least 20 minutes to act. Or just as often, the victim's symptoms could not possibly have been caused by the substance given. Many readers would not know the difference , but those who do find the story ruined because of it.
Until now, the writer has had trouble finding correct information about poisons. The writer Agatha Christie had the advantage of working in a hospital pharmacy during World War I. Most other writers must ask questions where they can and go by what little information they have, or they struggle through materials written in medicalese, trying to make sense of such terms as tachycardia, oliguria, or uremia.
The book's goal is to give the average writer correct information on poisons. However, as a writers' interests vary, so does their understanding of medicine and chemical science.
Poisonous chemicals are not to be taken lightly in real life, but the right poison can move the plot of a good story along nicely - and how nice it is to have correct facts.

Here is an example of what you can find. I choose the mandrake because is very difficult to find and I don't want to post extremely dangerous things on the internet!

Name: Mandrake (poisonous plant) Scientific name: Mandragora officinarum. Other: Devil's Apple, loveapple, mayapple.
Toxicity: Very toxic (in a scale of 1 to 6)
Location: The yellow plumlike fruit is found in the Middle East. During wheat harvest time, it is ripe and smells sickeningly sweet.
Deadly Parts: The rootstock, stem, flower, leaves, and unripe fruit. When completely ripe (yellow and soft), the fruit can be eaten without harm but not in quantity. The plant contains several hallucinogenic alkaloids, including hyoscyamine (atropine) and mandragorin.
Effects and Symptoms: Primary symptoms are severe diarrhea with vomiting, insensitivity, heavy sedation, coma, and death. The atropine tends to reduce secretion, decrease gastric juice, and shut down the intestines. Mandrake also causes pupil dilation and slowed heart rate.
Reaction Time: A few minutes to a half an hour.
Antidotes and Treatments: Gastric lavage and symptomatic treatment.
Notes: Mandrake was well known in biblical times as a fertility drug. In the Middle Age, mandrake was famous as a love-potion ans was used in incantations and considered a charm against evil spirits. In 1630 in Hamburg, Germany, three women were executed for possession of mandrake root, supposed evidence that they were involved in witchcraft. The mandrake has a large root, dark brown and rugged, resembling, to some, the male organ. According to superstition, it would kill a man to touch it fresh, and so a dog was used to pull it out of the ground. Supposedly, the mandrake would shriek and the dog would die.
Mandrake is now regarded as an anesthetic, cathartic, emetic, hypnotic, narcotic, and nervine.

*I found this information on a book called Deadly Doses a Writer's Guide to Poisons from Serita Deborah Stevens with Anne Klarner.