スギの胚發生について

抄録

The archegonia of Cryptomeria japonica D. Don are formed as a complex in an apical part of the female gametophyte. In the outside of the archegonial complex a layer of poorly differentiated jacket cells is found. In the inside of the complex the sterile tissue as is found in Cunninghamia is not formed. Two male gametes are formed by a division of a body cell. Both gametes formed in this way are equal in size and shape, In 1943, the fertilization took place in the end of June in Sendai. As a result of the division of a fertilized nucleus the proembryo of 16 cells is formed. The components of an embryo system are as follow : the open cells, the prosuspensor, the massive secondary suspensors and embryo propers. The separation of the prosuspensor cells in the early stages is not observed. On this point the writer′s observation does not agree with Buchholz′s result. The cleavage polyembryony always takes place. The rosette embryo is rarely formed by the division of the separated prosuspensor cells having no embryonic cell at their apex. The type of embryogeny in Cryptomeria is considered to be the same as those of Taiwania and Taxodium but totally differs from that of Cunninghamia.