Parabolic Systems of Differential Equations with Time-dependent Coefficients.

gut, resulting from the shift to the right side, of tissue derived from the left side of the embryo. Rightness and leftness of derivation are maintained and can be observed in later development when these regions have been stained. When stain was localized in the right wall of the duodenum after application to the right or midventral region in the level of the prospective duodenum, or posterior to this level, the asymmetry of the gut and associated structures was perfectly normal. Interference with normal development on the left side in the region of the prospective duodenum results in reversal of symmetry (situs inversus viscerum). The dominance of a more active growth potential on the left side at this level insures normal asymmetry of the gut.