TypescriptM.A. University of Missouri 1910Numerous observations on various phases of growth are to be found in the biological literature. Most of those concerning prenatal growth are upon the human embryo; although scattered observations are also recorded on other mammals, and a few on the lower vertebrates. The work presented in this paper was done in the attempt to trace, in the pig, the course of the prenatal growth of the body and of the various organs. The results are also compared with the course of growth in the human species and in the lower mammals, so far as data are available. The work was done in the Anatomical Laboratory of the University of Missouri, under the direction of Dr. C. M. Jackson, to whom I am deeply indebted for his interest, aid and valuable suggestions