The pentose nucleic acid of the pancreas is a representa- tive of a new type of nucleic acid, a pentose penta-nucleotide. It is composed of 3 molecules of purine nucleotides (2 molecules of guanylic acid and 1 of ade-nylic acid), together with 2 molecules of pyrimidine nucleotides. The acid is insoluble in water and in glacial acetic acid.