ichthin

from The Collaborative International Dictionary of English v.0.48

Ichthin \Ich"thin\ ([i^]k"th[i^]n), n. [Gr. 'ichqy`s fish.]
   (Physiol. Chem.)
   A nitrogenous substance resembling vitellin, present in the
   egg yolk of cartilaginous fishes.
   [1913 Webster]