Broader definitions of chemicals or chemical substances can be found, for example: the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including â (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature.
The major groups of worms include various species of flatworm, annelid, ribbon worm, spiny-headed worm, and aschelminth. Worms typically have an elongated, tubelike body, usually rather cylindrical, flattened, or leaflike in shape and often without appendages.
Ascaris is an intestinal parasite of humans which is the most common human worm infection. Adults of Ascaris lumbricoides are large roundworms,15-31 cm long with a curved tail (see the picture), while females are 20-35 cm long with a straightened tail. Ascaris hardly moves.