tokens: 2 g / dl , splenomegaly 2 - 3 times normal , and testicular atrophy approximately half normal weight ) after 12 doses of carbon tetrachloride given intragastrically in the phenobarbitone - primed rat was increased from 25 % to 56 % by giving the initial " calibrating " dose of carbon tetrachloride at the peak of the phenobarbitone - induced enlargement of the liver .