The course of the mitotic cell divisions was successively observed in living spermatocytes of the shield-bug, Graphosoma rubrolineatum, by phase microscopy with the application of a liquid paraffin culture technique. Based on the relationship between the behavior of the chromosomes during division, and the shortening and elongation of the cell axis, the suggestion was made that the migration of the chromosomes to poles is to be due to the contraction of the spindle fibers (the chromosomal fibers).
The present paper deals with the investigation of chromosomes in Plantago lanceolata L., finding the karyotype of the somatic chromosomes and chromosome behavior in meiotic divisions. Karyotypically the somatic complements of this plant consists of five kinds of chromosomes as shown Fig. 4. The meiotic divisions were observed; proceeding regularly.
Females of Sa.-B (Sapporo) strain were crossed with males of Hi.-A (Hirosaki) strain. And a female of Sa.-A strain was crossed with a male of Ni.-A (Niigata) strain. All individuals of the first generations were males, as shown in Table 1. As already pointed out by Goldschmidt ('34), these results are indisputably due to sex reversal of the genetical daughters (XY) into the males. All of these are not able to be distinguished from the normal males (XX) in their external characteristics, as well as in the structure of testes. In the reciprocal crosses attempted, the females produced normal sons and daughters (Table 2).
1) The relation between the vertical distribution and the polyploidy of Rubus has been investigated in six mountains which are from about 1000 to 2000 meters above the sea-level in Ehime Prefecture in Japan, and as the result the following data have been obtained. 2) The upper limits of vertical distributions of the nine diploid species of Rubus are found at least more than 900 meters high, while those of four of the tetraploid and hexaploid species are less than 850 meters at the highest. Though the upper limit of vertical distributhion of R. pectinellus (6X) is 1250 meters high, yet this is much lower than those of most diploid species. The average altitude of upper limits of the diploids is 1524 meters, while that of the polyploids is 750 meters, with the ratio of two to one, and the average distance between the upper and the lower limits of vertical distributions of the former is 650 meters, while that of the latter only half as many. 3) When all these data are taken into account, it may be safely said that the diploid species are generally distributed from low to high regions of the mountains, while the ployploid species are confined to the lower. And one of the chief reasons of this phenomenon may be that many of the former pass the winter with the winter buds, while the latter evergreen, and so they are more apt to be affected by bad environment than the former.