Carbon disulphide: a chemical used to kill insects.
Carbonic acid gas: a gas consisting of carbon and oxygen. It is produced by breathing, and whenever carbon is burned. It is the source of the carbon in plants.
Cereal: the name given to grasses that are raised for the food contained in their seeds, such as corn, wheat, rice.
Cobalt: a poisonous chemical used to kill insects.
Cocoon: the case made by an insect to contain its larva or pupa.
Commercial fertilizer: an enriching plant food bought to improve soil.
Compact: a soil is said to be compact when the particles are closely packed.
Concentrated: when applied to food the word means that it contains much feeding value in small bulk.
Contagious: a disease is said to be contagious when it can be spread or carried from one individual to another.
Cross: the result of breeding two varieties of plant together.