“…This enzyme once thought to be present only in ureotelic species (Clementi, 1937) now appears to be widespread throughout the animal kingdom. Characterization data have been reported for an oligochaete annelid (Bishop & Campbell, 1965: Red dy & Campbell, 1968), a crayfish (Hartenstein, 1971), a mollusc (Camp bell, 1966), insects (Reddy & Campbell, 1969a), amphibians (Soberbn ~ al., 1967;Carlisky & Sadnik, 1972), reptiles and birds (Mora et al, 1965;Brown, 1966), and manunals (Greenberg, 1960;lIirsch-Kolb ~al. , 1970) • Several research groups have reported significant differences in arginases from ureotelic, uricotelic, and ammonotelic organisms with re spect to antigenic properties, molecular weights, Michaelis constants, substrate inhibition, and stability during dialysis (Mora et al, 1965(Mora et al, , 1966Soru, 1965;Brown, 1966;Soberon, et al, 1967;Reddy & Campbell, 1968, 1969aRossi & Grazi, 1969;Middlehoven, 1969;Hirsch-Kolb ~t al., 1970).…”