The formation of the prolamellar body was studied using the seedlings of Cucumis sativus in relation to the development of lamellar structure in the plastids. The seedlings were grown in the light for various lengths of time, and then transferred to darkness. The prolamellar bodies were formed in a plastid in the dark, and increased in number as the lamellar structure developed. The formation of prolamellar bodies in the plastid, in which the grana lamellae differentiate, seems to occur only in the region of intergrana lamellae. Besides, the present experiment showed that the prolamellar bodies in continuous dark are devoid of lamellar structure, and that they are also produced when the seedling is transferred to the darkness at its earlier stage of development. Moreover, the prolamellar body and lamellar structure are formed simultaneously under the weak light condition, while the former disappears under stronger light. From these observations, it is suggested that the appearance of prolamellar body may be caused by blocking the conversion of vesicles into lamellae.
The apparent photosynthesis-temperature relations of some aquatic plants were examined with the differential gas-volumeter at the light intensity of 20klux. The optimum temperature for photosynthesis was found at 20°in Nitella sp. and Fontinalis hypnoides, and at 30°in Ceratophyllum demersum, Potamogetoncrispus and Cabomba caroliniana. The maximum apparent photosynthetic rates of these plants were 3.62, 4.75, 4.43, 4.50 and 3.86μl O2/dry mg/hr, respectively. Seasonal changes in the relationship between the apparent photosynthesis and temperature were examined for C. caroliniana. The maximum photosynthesis was obtained at the same temperature (about 30°) through three seasons; May, August and December, while a noticeable variation of the photosynthetic rate was observed among these seasons.
In the shoot of Ambrosia artemisiaefolia var. elatior, four to nine pairs of decussate leaves are produced above the cotyledons before the spiral phyllotaxis appears. In the transitional region of the phyllotaxis, several pairs of leaves still retain the character of decussation, because two leaves of each pair arise on not much different levels on the stem and the divergence angles between leaves in this transitional region do not deviate much from those in the descussate phyllotaxis. In the shoot apices of growing plants with the spiral phyllotaxis, the number of contact parastichies is at first (2+3), and then it changes to (3+5). The progressive increase in the relative size of the apical dome to the leaf primordium might be one of the causal factors for the phyllotactic change from the decussate to the spiral system and that from the lower parastichy system to the higher one. The apical meristem of the shoot consists of a two-layered tunica and a corpus. The leaf primordium is originated by periclinal cell divisions in the second tunica layer on the flank of the apical dome. No fundamental difference was found in the structure of the shoot apices with the decussate and the spiral phyllotaxis.
The chromosome numbers and karyotypes of Pollia japonica Thumb. and Aneilema Keisak Hassk. were examined, and determined to be 2n=32 and 2n=40 respectively. These somatic numbers (2n) differed from those reported formerly by others. But on the basis of available data, it is difficult to explain the reason for the presence of numerical differences in chromosomes of the same species. The karyotypes of these species were as follows: The karyotype of P. japonica was showed to be K=2n=32=4Am+4Bsm+4Cm+4Dm+4Esm+4Fsm+4Gst+4Hm; eight pairs of chromosomes with median primary constriction, six pairs with submedian and two pairs with subterminal. Each pair was no satellite, but two pairs of nucleolar chromosomes were observed. The karyotype of A. Keisak was showed to be K=2n=40=4Asm1+2csAsm2+4Ast3+6Bsm1+2Bst2+2Csm1+6Cm2+10Dsm1+2tDm2+2Dm3; five pairs of chromosomes with median primary constriction, twelve pairs with submedian three pairs with subterminal. One of five pairs of chromosomes with median primary constriction was the satellite chromosomes and one of twelve pairs with submedian was with secondary constriction in their long arms.
The somatic chromosome numbers of three species and two varieties of Hosta were ascertained: H. tardiva, H. undulata and its var. albomarginata are 2n=60, H. undulata var. erromena 2n=62 and H. sacra 2n=63. The karyotypes of H. undulata and its var. albomarginata were as follows: the 60 chromosomes were in 30 pairs, which could be classified into four pairs of large chromosomes, two pairs of medium ones, and 24 pairs of small ones. In H.undulata var. erromena, two of the medium chromosomes and two of the small ones were not exactly same in size and shape. These three entities are, from their karyotypes, considered to have descended from H. lancifolia. In H. tardiva, two of the large chromosomes and two of the medium ones were remarkably different size and shape. The 63 chromosomes of H. sacra could be classified into four pairs of large chromosomes, two pairs of medium ones, 51 small chromosomes of which 50 were in pairs. H. sacra seems, judging from their geographical distribution and karyotype, to have derived from H. sieboldiana.