“…A number of enzymes somewhat resembling DNase I1 have been described in many tissues, e.g., parotid gland (216), adrenal medulla (212), myocardium (217), chick liver (139), rat liver nuclei (224)' neurons (43), rabbit leucocytes (34), developing mouw embryo (215), cerebral tissues (227), and in genital secretions of bulls (242). An increase in the DNase I1 level in thymus and in spleen (116) was noted during the maturation of mice, The levels of DNaseII and DNase I type enzymes were determined daily during development of the chick embryo (228).…”