1) The relation between nucleolus and nucleolar chromosomes in polyploid series of Scilla japonica (18=B2B2, 26=B1B2B2, 34=B1B1B2B2, 35=B1B2B2B2) was explained by the balance hypothesis of nucleolar chromosome. 2) Paris hexaphylla (2n=15) is triploid and has ogle sat- and two nucleolar chromosomes, corresponding to three nucleoli at telophase. The satellite in Paris consists of heterochromatin and seems to be genetically inert. 3) Brodiaea uniflora (2n=12) is diploid and has only one nucleolus, corresponding to one sat-chromosome with a long stalk. This fact seems favourable for the balance hypothesis of nucleolar chromosome.
1. In the culture solution, which was purified from heavy metal impurities by the adsorption procedure with calcium phosphate, and to which Fe was then added, Spirodela and Lemna could not grow and sooner or later died, if Mn was not added. 2. The minimum concentration of Mn in the culture solution, which was enough to permit the new growth of Mn-deficient plants of Spirodela, was about 5×10-10mol. 3. In the medium containing Mn in concentration of 10-9mol, the vegetative propagation occurred continuously, but fronds remained very small, the growth of roots was extremely retarded and chlorosis occured. In the medium in which the concentration of Mn was increased to 5×10-9 mol, fronds were still smaller than the normal ones, but in other appearances they were almost similar to each other. For the normal growth of Spirodela Mn was required in the concentration of 10-8mol. In the medium with more Mn (10-7mol and 10-6mol) no difference was visible from the case of 10-8mol, concerning the rate of vegetative propagation, the size of frond, the growth of root and other appearances. 4. From the culture experiment of Spirodela, it may be concluded that the culture solution, which was purified by the adsorption treatment with calcium phosphate, does not contain Mn in a higher concentration than 5×10-10mol. 5. Mn is reserved in the body of Spirodela, and the amount contained in one plant of 4 or 5 fronds, is sufficient to cause a new growth and vegetative propagation from a Mn-deficient plant, which is cultured in 100cc. solution. Its concentration corresponds to 10-8mol. 6. Dry weight of Spirodela and Lemna in the culture with Mn amounted to 40-300 times as much as that in the Mn-deficient culture.
A number of chromosomes of Carex podogyna was reported as 2n=76 by OKUNO (1940), while other two chromosome numbers of 2n=68 and 2n=72 have newly been found in the materials used in the present investigation. Reduction divisions of the four plants studied showed that three have 2n=72 and one has 2n=68. Chromosome behavior in meiosis of the plants with 2n=72 were quite normal, forming regularly 36 bivalents in the first metaphase and 36 chromosomes in both second and the primary pollen nuclear division metaphases (Figs. 1-4). While in meiosis of the plant with 2n=68 some structural hybridities were found (cf. Table 1, Fig. 5-16). It is premature, however, to discuss the origin of intraspecific aneuploidy of this species until further cytological investigations of many plants as well as related species are carried out. It is suggested, however, that the present intraspecific aneuploid plants may be the derivatives of high polyploidy (cf. TANAKA, 1940d). Among the pollens of the plant with 2n=68, an abnormal diploid pollen (Fig. 16) was found, which has two apical nuclei in stead of usual three. Therefore apparently two daughter nuclei of the quartet male nuclei which resulted by the meiotic process seem to survive as the pollen nucleus. This fact probably suggests the possibility that by the doubling or combination of chromosome sets more than one nucleus servive as the pollen nucleus (cf. TANAKA, 1941).
1. Details of the detection method of growth-inhibiting substance obtainable by keeping the agar block in contact with the upper cut surface of the petiole segment, are described in this report. The Avena-technique is used. 2. As the number of petioles per agar block increases, the positive curvature of the Avena-coleoptile becomes larger. 3. The maximum curvature of the Avena-coleoptile is got by one hour contact of the petiole with the agar. 4. The longer the length of the petiole-segment is the larger the curvature of the Avena-coleoptile becomes. 5. The maximum positive curvature of Avena-coleoptile is got by three hours contact of the agar with the coleoptile. 6. In the case of the agar block rich in the inhibiting substance, it requires 2 1/2 hours to get the coleoptile curvature larger than what is caused by the blank agar; while, in the case of the agar block, containing small amount of the inhibiting substance, it takes 3 hours.