The Collaborative International Dictionary of English v.0.48:

Echidnine \E*chid"nine\ (?; 104), n. [See Echidna.] (Chem.)
   The clear, viscid fluid secreted by the poison glands of
   certain serpents; also, a nitrogenous base contained in this,
   and supposed to be the active poisonous principle of the
   virus. --Brande & C.