Liquid

After a worm was cut into two, it could grow into two worms. First, the cut tissue would contract and part of the muscle would dissolve to form a new cluster of cells. The white blood cell would collect at the cut surface to form a clog to heal up the worm to prevent blood loss, and infiltration of micro-organism. After that, the worm could survive and enter regeneration status. Currently, there is still mystery about the worm's regeneration mechanism but mainly there are two theories about it. 

One is after the body cavity closes, the original cells within the body cavity would move to the cut surface and form a clog with dissolved muscular cells. At the same time, rapid mitosis would occur within the body to regrow back the cells in the digestive system, nervous system and capillary system.