What the Mangold-Spemann experiment demonstrate

1. An identical twin results when a cell from a blastopore stage (or earlier) embryo separates and develops on its own. How is it that the left-behind developing embryo can lose a cell and still develop normally? 2.Propose an explanation for why evolution has produced centrally organized nervous systems in vertebrate animals, but decentralized nervous systems such as are often found in invertebrates. 3.What did the Mangold-Spemann experiment demonstrate?