Data were collected from a colony of 49 male and 55 female twoyear-old Mongolian gerbils, Meriones unguiculatus (Milne-Edwards, 1867). This report gives tables which present data regarding linear measurements of body and organs and absolute and relative organ-weight data. The means, stafldard deviations, ranges, and coefficients of variation were summarized in the tables. Grossly observed pathological organs were omitted from the study. The tables give information about this species which could be helpful in future laboratory investigations where the bodyand organ-weight ranges, variability and linear measurements of this species may be of practical value.The literature contains many references in which various species of Gerbillinae have been used for research purposes. The references below indicate a recent interest in the use of the species presented here, the Monoglian gerbil, Meriones unguiculatus, (Milne-Edwards, 1867). This study was initiated because of the increased interest in this animal and the lack of quantitative information regarding body-weight and organ-weight data in adult male and female gerbils.Some metabolic characteristics of this essentially desert rodent, which included determinations of critical body temperature, thermal neutrality, heat tolerance, oxygen consumption, and metabolic rate, were done by Robinson ('59). This gerbil responds to the oral administration of cholesterol with a marked elevation of blood cholesterol, but without any significant atherosclerotic plaque formation (Clarkson, King and Warnock, '57; Gordon and Cekleniak, '59 and '61). Besides these studies other investigations encompassing a variety of factors affecting blood cholesterol levels in this animal have been reported by Gordon, Stolzenberg and Cekleniak ('59); Gordon and Cekleniak ('60 teins by Dellenback and Ringle ('63). Animals of this species have been trained for use in investigations of conditioned avoidance-escape behavior for the differential evaluation of drugs affecting the central nervous system ( L a t h e r and Cekleniak, '64).In the search for suitable vertebrate hosts for model parasitic infections, Meriones unguiculatus has been infected with Nematospiroides dubius in a study by Cross and Scott ('60), with Trichostrongylus axei by Leland ('61), with Leptospiru pomona by Lewis and Gray ('61), with Haemobartonella by Najarian ('61), and with Echinococcus multilocularis by Norman and Kagan ('61 ).
MATERIAL AND METHODSThe original stock of Meriones unguiculatus was obtained from the gerbil colony at Tumblebrook Farm, Brant Lake, New York.Random inbred pairs of animals were kept in metal cages, 10 X 15 inches, with two inches of Sterolit animal bedding and a four-inch diameter, clay flower pot for additional seclusion.Nineteen females were bred and produced 26 liters of 4 to 9 animals per litter, with an over-all average of six per litter. After four weeks, the males and females of each litter were placed in separate cages. All animals were maintained on a diet consisting of 10% sunflower se...