Bacterial cytokinesis begins with the assembly of FtsZ into a Z ring at the center of the cell. The Z-ring constriction in Gram-negative bacteria may occur in an environment where the periplasm and the cytoplasm are isoosmotic. but in Gram-positive bacteria the constriction may have to overcome a substantial turgor pressure. We address three potential sources of invagination force. https://www.roneverhart.com/Ryukyu-Kobujutsu-Buki-Jutsu-Vol-2-DVD-with-Kiyoshi-Yogi/