1) The fine and coarse structures found in the living nuclei in the staminate hair and leaf hair cells of Tradescantia are mutually transformed by the aid of water or hypertonic solutions. 2) The transformation of the fine structure to the coarse one is also made by exposing the cells at high temperatures which cause the dehydration of the nucleus. 3) It is observed that in Tradescantia, the guard cell nuclei of stomata show the coarse structure when the stomata are in an open state and accordingly when the nuclei are in a dehydrated state, and the fine structure when the stomata are in a closed state and the nuclei are in a hydrated state. 4) Roughly speaking, the chromonemata in the nucleus of the fine structure assume the spiral and those in the nucleus of the coarse structure the twisted configuration. 5) The extremely thick nuclear threads in the erythrocyte nuclei in Triturus are observed both in the living and in the fixed state, and they are demonstrated by an artificial dissolution method to contain chromonemata within.
1. It is contended that the chromonema must be a natural structure. 2. The results of observations presented in the present paper are as follows:- a) The chromonemata are visible in living chromosomes in prophase, in the spiral stage in the natural state and in the mid-prophase in a hydrated state. b) In the very beginning of mitosis the nucleus is hydrated probably preceded by a dehydration of the nuclear elements. As a result of these dehydration and hydration the interchromosomal spaces first become visible. c) Then the twisted configuration or “dotted structure” of the nuclear threads in the preparatory stage of mitosis is transformed into the spiral configuration, thus the spiral stage being reached. The transformation begins with the swelling of “dots” indicating that in this outward aspect the spiral turns of the tightly twisted form are loosened gradually by hydration to reassume the regular spiral form.
1. It is demonstrated that mitosis can be abbreviated at any stage of prophase. 2. A diffuse stage is observed in mitosis, which occurs in the midprophase. 3. On the basis of these facts, the origin of interkinesis is considered, and a comparison of the stages in meiosis with those in mitosis is attempted. The difference in nature between the somatic and the meiotic reduction division is also considered.
1) There are no heterochromosomes in Crustacea Isopoda, neither in the male, nor in the female. 2) The haploid chromosome number of the marine Isopoda and of the related terrestrial and freshwater species is 28 or near to 28: 3) The species of the genus Asellus have a haploid chromosome number of 8. These 8 huge elements result from the fusion of the small and d numerous chromosomes of Stenasellus. 4) The chromosome number of the true Oniscoidea (Endophora and Embolophora) is progressively increasing. The chromosome evolution is parallel to the morphological evolution. We can summarize it as follows: The most extreme terms have the same high chromosome number, while the intermediate species have smaller numbers, resulting from fusions and associations of chromosomes.
1. Coichicine was used to induce polyploidy in Habrobracon pectinophorae. Eggs, larvae, pupae or adults were treated by 0.025, 0.05 or 0.1 percent aqueous solution of colchicine for various length of time. 2. 0.05-0.1 percent solution of this chemical was effective for the production of polyploidy. 3. Polyploidy was obtained in the spermatogonial cells by treating the male larvae. These cells, however, seem to degenerate without becoming functional sperms. 4. On the other hand, tetraploid oogonial cells induced by the treatment of adult females may become tetraploid eggs, which, after reduction, develop into impaternate diploid females or diploid males. 5. Thus 130 impaternate females and at least 6 diploid males were produced by 44 treated females. 6. Many abnormal males and females with very short antennae were produced by the treatment of larvae. 7. Abnormal males having defects not only in external genitalia, Malpighian tubules, but also in gut were produced by the treatment of ovarian eggs. I wish to express my heartfelt gratitude to Prof. Taku Komai for his suggestion of the work and also for his kind guidance in the course of the experiments.
1. Small granules like nucleoli appear in the resting nucleus and also in the nucleus in the mitotic prophase. They extrude into the cytoplasm or into the vacuoles in it. These granules will be called the nuclear granules, each nuclear granule consisting of a central grain and the outer swelling portion. They swell easily under certain condition in the nucleus and have an important role in the vacuole formation. The extrusion of the nuclear granules occurs in the healthy cells, and it does not prevent the course of the chromcsome formation in the mitotic prophase, so that it is not pathological phenomenon. 2. Extruded nuclear granules absorbing water in the cytoplasm develop into the vacuoles, but often they enlarge in the older vacuoles and replace them. These vacuoles (n-vacuoles) showed several different characters among themselves; consequently I have concluded that the nuclear granules are of different kinds and that the substances in the cytoplasmic vacuoles are mostly the direct derivatives of the nucleus. The substances are probably the products of the chromonemata. It is also possible that the nucleolus is a special kind of nuclear granules. 3. It is not improbable that the Golgi-apparatus has a certain relationship with the nuclear granules, or n-vacuoles. 4. The extrusion of the nuclear granules resembles the vacuolization in the nucleus mentioned by several investigators and considered as the first step in the degeneration or as the degeneration itself of the nucleus. In some cases, e.g. in the subepidermal cells of the young anther, it may be the first step in the degeneration of the nucleus, but on the other hand it is a normal process in the differentiation of the cells or tissue. Here I wish to express my hearty thanks to Prof. K. Fujii for his, constant encouragement and criticisms in the course of the investigation.
1. Fourteen varieties of gold-fish common in Japan, together with the Funa and the Hibuna, both of which are known to be the prototypes of the former, have been karyologically investigated in this study. In all these forms the normal or basic number of chromosomes is 94 forming the diploid complement (in the spermatogonium) and 47 for the haploid (in the spermatocytes). The chromosomes are all telomitic and rodshaped showing a slight difference in length. Morphologically the chromosome complex of the Funa and of all the varieties of the gold-fish herein investigated are in complete agreement with one another, both in number and in shape. And thus, there is not the least evidence for the occurrence of the polyploid relationship among the gold-fish varieties. The karyological relationship between the two allies, the carp., Cyprinus carpio and the Funa, Carassius carassius, (the gold-fish also) has been considered. 2. Occasional occurrence of cells with univalent chromosomes at first metaphase, which is probably due to the failure of the meiotic chromosome pairing, has been observed in nine of the varieties herein deait with. Generally two univalents per cell seem to be most common throughout the forms observed. Four is the most frequent of the higher numbers, but a number as high as eight per cells has been observed. A rough estimate shows that cells with univalents seem to occur in a rather high frequency. No definite explanation regarding the cause or causes of the formation of univalents has been offered; but the bearing of the chiasma theory and of comparable phenomena investigated in plants on the observations herein recorded has been considered.
PART II. GROWTH, DIVISION AND INCREASE IN NUMBER OF MULTIPLE NUCLEI 1) The quantitative relationships between the multiple nuclei and the cytoplasm in the vegetative cells of Actinosphaerium eichhorni are studied from the cytometrical view-point. The term “cytometry” is proposed to denote the biometrical works on the parts of the cell. 2) Comparative measurements have been made on cell and nuclear diameters in the living state and on permanent preparations. Thus the reciprocal of the shrinkage index, 1.15±0.013, has been determined for multiple nuclei, and used for obtaining the original size of the nuclei. 3) The average diameter of multiple nuclei is nearly constant (7.8μ) in the cells reared under the same condition. Strictly speaking, however, the deviation of the average diameter within 3% is found among the cultures: this seems to be due to the minute inequalities in the culture conditions such as quantity of food and age of strains. 4) The fluctuation in size and number of multiple nuclei which is found in a single cell as well as in different cells can be ascribed to the growth and subsequent binary fission of multiple nuclei as represented by the following schemata:- l13→l23= 2l13→2l23 (for one nucleus) nl13→nl23=2nl13→2nl23 (for n nuclei) where l1 and l1 are diameters of nuclei and n the nuclear number in a cell. This means simply that doubling of unit volume of multiple nuclei is invariably followed by nuclear division and increase. The constancy of average diameter of multiple nuclei (3) is expected theoretically from this relation. The data obtained by actual measurements have been found to follow the schemata very well. PART III. CYTOMETRICAL BASIS FOR THE DIFFERENTIATION OF MULTIPLE NUCLEI 5) The number of multiple nuclei accords very well with the general allometrical formula y=b Lα, in which y is the value in question and L is the cell diameter left out the dimension μ while b, a are a set of constants. The term “nuclear constant” is proposed for a designating the nuclear number. Four old cultures out of the six examined had the nuclear constant of approximately 2, while the rest, one newly germinated and the other rather over-fed, had the values between 2 and 3. The nuclear constant in the newly germinated culture decreased to nearly 2 about a half month later: this offers an evidence that the nuclear constant changes according to conditions, both internal and external. 6) A definite value of nuclear constant is found in all vegetative cells of the same culture with diameters ranging from 45μ to 171μ. 7) Six fundamental quantitative relations existing between multiple nuclei and cytoplasm have been considered cytometrically from the viewpoint of the surface law of comparative physiology. The actual data agree well with the theoretically expected values. 8) The nuclear volume-cell surface area ratio or nucleo-surface ratio and the nuclear surface area-cell surface area ratio are given by 3 the formulae bl3/6Laand bl2Larespectively. They are constant regardless of the difference in cell size when a=2 (therefore a=0), and increase in exact proportion to the cell diameter when a=3 (therefore a=1). 9) The nuclear volume-cell volume ratio are given by the formulae bl3L-1 a and 6bl2L-1+a respectively.