The relation of cell size to body size is a problem which received a great deal of attention some years ago, and the general coiiclusion which was reached after extensive researches was that, within a species, larger individuals ordinarily are made up of more cells than small ones and that the difference in body size is not due to larger cells.2 By implication, this conclusion requires that in larger individuals either the rate of cell division is higher (continuously or at some period) or that it is continued for a longer time.
During the course of a cytological study of the amnia of hybrid rabbits derived from a cross between a Flemish Giant doe and a Polish (dwarf) buck, it was noted that the amniotic cells of the hybrids are markedly larger than similar cells from ordinary rabbit embryos of the same age. I n drawings given in an earlier paper (Painter, '26) ordinary rabbit amniotic cells measure from 3 to 4 cm. in diameter, as reproduced under constant magnification, whereas in hybrids the range of size is from 5 to 6 cm. The hybrid embryos are much larger than common-stock embryos of the same age, and these observations on cell size suggested that, perhaps, the rabbit is an exception to the general rule concerning the relation of cell size to body size. It was with a view to testing Contribution no. 214 from the Department of Zoology, University of Texas. * A full review of this subject together with citations to pertinent literature is Exceptions to the general rule are also diwussed The experimental portion of this work was done at the Bussey Institution.
given by Wilson ( '25), p. 97. by this author.