Final answer:
Eating grain infected with Claviceps purpurea can cause the disease ergotism, which has two forms: gangrenous and convulsive. Gangrenous ergotism leads to improper blood flow, resulting in gangrene, while convulsive ergotism affects the central nervous system, causing mania and hallucinations.
Step-by-step explanation:
The mold of Claviceps purpurea occasionally grows on grain, especially rye. Eating infected grain can result in a disease called ergotism. Claviceps purpurea produces a mycotoxin called ergot toxin, which can cause two forms of ergotism: gangrenous and convulsive. In gangrenous ergotism, the toxin leads to improper blood flow to the extremities, resulting in gangrene. In convulsive ergotism, the toxin affects the central nervous system, causing mania and hallucinations.