抄録
In a previous paper a practical method of manufacturing crude vitamin B_<12> from the carbon cake, on which vitamin B_<12> in the activated sludge was adsorbed, has been reported by one of us. In this paper the toxicity of that crude preparation was examined in mice. When the product was mixed with the mouse-ration and administered in a dosage equivalent to 5,25 od 50 μg vitamin B_<12>-activity/kg of body weight per day for 30 days, neither its inhibitory effect upon growth nor any toxic reaction was observed.
