IT is generally acknowledged that land-living plants have sprung from some algal source: that the land was invaded and that the invaders show form and structure adapted to sub-aerial life. If this be ...

All vertebrate embryos follow a common developmental path due to their common ancestry. All have a set of very similar genes (the homeobox genes) that define their basic body plan. As they grow, the ...

THE first part of this book deals with those embryological processes which are common to most of the higher animal forms, and presents in assimilable form the accepted views on cleavage, germ layer ...