1. Thirty-two single lambs were grazed together on pasture. At weekly intervals, from birth to 112 days of age, two lambs were slaughtered and various organs weighed immediately after death. Also the alimentary tracts of seven adult sheep were obtained immediately after death.
2. The rumen had the fastest growth rate of the four stomachs, followed by the reticulum, omasum, and abomasum, in that order.
3. Immediately after birth the four stomachs altered rapidly in their relative proportions, but by about 66 days of age they had reached approximately adult proportions.
4. The weights of the liver, heart and kidneys, relative to live weight, decreased during the first few weeks of life, and thereafter remained constant.
5. The weight of the spleen, relative to live weight, increased during the first week of life and thereafter remained constant.