grown most rapidly through fortuitous circumstances, probably depending upon both innate and environmental factors. None of the woodrats handled was excessively fat, nor were any emaciated. The habit of keeping on hand stores of food at all seasons perhaps obviates the necessity for storing quantities of fat. Seasonal trends in weight vary among individuals, and are not wholly consistent from year to year. Rainey found that in late autumn and winter, rats steadily gain weight reaching a peak in late February or March. However, in the winters of 1948-49 and 1949-50, Fitch found that most rats lost weight and hardly any, even those that were short of adult size, made gains. The following records of a male born in the spring of 1949 show rapid growth and attainment of adult size in his first summer, cessation of growth during the winter, and resumption of growth, with attainment of near-maximum size the following spring. June 16, 1949 96 gms. September 26, 1949 230 gms. September 27, 1949 230 gms. October 18, 1949 260 gms. October 27, 1949 250 gms. October 29, 1949 220 gms. November 8, 1949 235 gms. November 15, 1949 245 gms. November 24, 1949 240 gms. November 26, 1949 240 gms. November 30, 1949 240 gms. December 20, 1949 260 gms. February 18, 1950 230 gms. April 5, 1950 290 gms. April 7, 1950 300 gms. October 7, 1950 320 gms. November 29, 1950 345 gms. March 23, 1951 340 gms. Another example, showing winter cessation of growth in a male at even smaller size is shown below. This was in the winter of 1950-1951. November 9 145 gms. November 28 175 gms. November 29 165 gms. January 10 180 gms. January 11 175 gms. March 1 225 gms. March 23 200 gms. _Longevity_