Crystals in supporting cells of pineal organ in larval lamprey not likely to be pure guanine.

Abstract

Spectrophotometry of larval pineal organs, digested in either 1 M HCl or 1 M NaOH, revealed peak absorbances at 253 nm and 268 nm, respectively. This result is not consistent with the view that the crystals found in lamprey pineals are chemically made of guanine.