For all various studies, the making and the development of proglottids has not been known as Braun's words "die näheren Vorgänge bei der Bildung der Proglottiden sind uns bisher noch ganz unbekannt." On cestode, we have nothing for the fundamental knowledge to the making and development of all gewebe and organe, namely, cuticle, muscle, nerve, excretoryorgane and genitalorgan. So I have observed the making and the development of proglottids of typical cestodes, Taenia pisiformis and Ditpylidium caninum since march 1941 under the kindly direction of prof. Dr. M. Suzuki. My main points of the results of the observation are as follows. 1. The fundamental mechanisms of the making and development of proglottids between Taenia pisiformis and Dipylidium caninum are completely same. 2. The making and development of proglottids of Taenia pisiformis and Dipylidium caninum is held out mainly at scorexbase and more at cervixand at first external proglottids were made, then proper proglottids developed from divisions mechanisms in those external proglottids. 3. Cuticle were made from circular cells in subcuticle celllayers, muscle were made from circular cells insiside subcuticle, fibrous tissue from cells in Parenchym. 4. Only genitalorgane wer made and developed newly in proglottids from circular cells in parenchym and subcuticle cells, but these Begining were looked erly in external proglottids and there were any difference between cells which make up cuticle and muscle of genitalorgane and cells which transform into keimcells at those form and dyeing. 5) And again I could not find any difference at form and dyeing between cells which made up cuticle, muscle, nerve fibres and cells which tranoformed into Hoden and keimstock. 6) In younger proglottids there were many those circulas cells in all tissues, but in older proglottids I could not observed these cells a few. 7) The nucleus of these cells are 2, 800-7, 600μ at Taenia pisiformis, 2, 600-4, 500μ at Dipylidium caninum in length at diameter, and coloured up violet with Hämatoxylin.