A fractionation by treating with activa ?? ed charcoal has been made of growth factors for chicks which were found in the boiled extract of the clam, Venerupis philippinarum.
A filtrate fraction which was obtained on treating a slightly acidic solution of the boiled extract with the adsorbent, still possessed growth factors in a con ?? iderable amount. This is not case with bovine liver extract. An eluate from the adsorbate with a dilu ?? e sodium hydroxide solution showed a growth promoting activity nearly equal to that of the filtra ?? e frac ?? ion. The a ?? say of vitamin B12 by Euglena gracilis indica ?? ed that 76 per cent of the vitamin in the extract passed into the non-adsorbed fraction, and that only 0.19 per (e ?? t was found in the eluate. It follows, accordingly, that growth accelerating activity manifested by the eluate must be due to the presence of some unidentifiel growth factor or factors, probably vitamin B15 postulated by TOMIYAMA and YONE2).
