GAMETE, in biology the name given to the special cells set apart in most plants and animals for sexual reproductive pur poses. (See SEX.) They are usually of two kinds: (I) the ovum, which is large, stationary and heavily laden with food-materials (yolk) ; and (2) the spermatozoon or (in plants) spermatozoid, which is small, actively motile and, in all animals except the Arthropoda (insects, spiders, crabs, etc.) and nematode worms, consisting of a head of nuclear material (see NUCLEUS) and a long vibratile tail. In the higher plants (conifers and flowering plants) and in many fungi, this element is much modified (see PLANT), but in most of the lower plants the spermatozoid closely resembles the animal spermatozoon. In some Algae (q.v.), both gametes are spermatozoon-like ; and in certain Algae and Protozoa the whole organism acts as a gamete. The two gametes, in all the above cases, fuse to form a zygote, which develops into the adult organism. An organism producing ova is said to be female, one producing spermatozoa, male : one producing both, hermaphro dite. (See SEX, HEREDITY, CYTOLOGY, HERMAPHRODITE, EM BRYOLOGY.)