||Lep"to*thrix (l&ebreve;p"t&osl;*thr&ibreve;ks), n. [NL., fr. Gr. lepto`s small + qri`x hair.] (Biol.) A genus of bacteria, characterized by having their filaments very long, slender, and indistinctly articulated.

||Lep"to*thrix, a. [See Leptothrix, n. ] (Biol.) Having the form of a little chain; -- applied to bacteria when, as in multiplication by fission, they form a chain of filiform individuals.