(1) Short-day plant, Salvinia natans was used as the material and the photoperiodism was studied. (2) In one cycle of short-day treatment 8% of plants formed sporocarp, but 80% in two cycles and 100% in seven cycles, and hence Salvinia plant is considered very sensitive short-day plant. (3) Nitrogen is effective upon the formation and development of the sporocarp. (4) In this experiment, the critical dark period could not be decided; it is considered that the critical dark period exists over 12hrs, in the combination with the light period of 16hrs. (5) Photoperiodic perception is performed only on the air leaf; the stimulus for the initiation of sporocary move to the growing point of the water leaves of the plant deprived of air-leaf. This fact is also the case with Spermatophyta. The writer must express here his gratitude to Prot. emer. Dr. Yoshizi YOSHII, Tohoku University, for his valuable guidance and to Prof. Naoyuki KUME of the Yoshida Branch of Kyoto University for his kindness in supplying material for study, and to the students who are specialized in plant ecology and plant physiology (Mr. Tokuzo ARAKI, Yoshiro KIZIMA, Tadatoshi, KIKUCHI Kenzi INAMORI) for their sincere assistance during the course of the experiment.
In the present paper reports are made on the structure of roots in Metasequoia and its affinity to other conifers as represented by the structure of roots. The results can be summarized of follows. 1) The structure of roots in Metasequoia is not much different from that of the other conifers. 2) According to the number of protoxylem Taxodiaceae can be divided into the following three groups: 1st Group……Diarch both in the long and the short root. Sciadopitys verticillata Sieb. et Zucc., Taiwania cryptomerioides Hayata, Cunninghamia lanceolata Hook. 2nd Group……Tri-, tetra- or polyarch in the long root and di- or triarch in the short root. Sequoiadendron gigantium Buch., Glyptostrobus pensilis Koch., Taxodiumdistichum Rich., Metasequoia glyptostroboides Hu et Cheng, Sequoia sempervirens End1. 3rd Group……Triarch both in the long and the short root. Cryptomeria japonica Don. 3) Differing from the second group to which belongs Metasequoia, the representatives of the first group have many remarkable characters in common. Their pollen tube branches and the proembryo has rosette-cells. 4) Among the representatives of the second group no remarkable difference in morphological characters are seen. It seems not adequate to separate Metasequoia from the other members as a representative of a special family, Metasequoiaceae.
In the present report, the result of cytological studies on the maturation division of PMC-s of TSF2 plants having 2n=42 chromosomes was described. These TSF2 plants, 24 in (total) were obtained in 1942. At the heterotypic metaphase in PMC-s of TSF2 plants with 2n=42 chromosomes, 7-21 bivalents and 0-28 univalents were observed (Figs. 1-5). The frequency of bivalents in the PMC-s was shown in table 1. In the case of fertile individuals the number of bivalents were found almost all to lie between 17 and 21, and of sterile individuals between 14 and 21. Tetravalents were observed, though rarely, in addition to bivalents at the heterotypic metaphase but no trivalent was found. Almost all the plants of the 24 individuals investigated may be considered as what might be called the eu-amphidiploid in which AB genomes of Triticum turgidum and R genome of Secale cereale are included completely. In most cases the distribution of chromosomes to the opposite poles at the anaphase in heterotypic division was observed to be 21:21 (Table 2). The nuclear plate showing 39II+6I chromosomes at the heterotypic metaphase of PMC-s was observed (Fig. 11). This case ought to be due to the duplication of chromosomes of AB genomes of T. turgidum and R genome of S. cereale. Further, the nuclear plate having 7II+14I chromosomes was observed. This case may be thought of as due to the deficiency of chromosomes corresponding to any two genomes (14 chromosomes) in AABB genomes of T. turgidum and RR genomes of S. cereale. 11 plants of the 24 individuals investigated were appeared to be fertile and the remaining 13 individuals sterile.