IN the rapidly-shifting condition of our knowledge of the development of all kinds of animals, it is a most difficult thing to produce a satisfactory treatise on Comparative Embryology. None the less ...

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 ...

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 ...

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in ...