Abstract
The total number of hepatic cells was detd. at frequent intervals during the 1st month of carcinogensis in the livers of rats fed 3[image]-methyl-4-dimethyl-aminoazobenzene; the large granule fraction was also isolated from these livers and the quantity of pentosenucleic acid and protein-N in this fraction of the avg. cell was detd. The total no. of liver cells remained in the normal range for 26 days, but between the 26th and 28th days a sudden increase of 50% occurred. No increase in total liver mass accompanied this increase in cell number, and evidence is presented to show that no net synthesis of large granule protein or pentosenucleic acid occurred during this cell division. This cell division without increase in cell substance is compared to the cell division induced in normal liver cells by regeneration.