1. Eight individuals of an F, hybrid of Paraixeris denticulata×Lactuca squarrosa were studied cytologically. 2. In the root-tips of the hybrid, cells with different chromosome numbers were observed, showing a predominance of cells of a definite karyotype with 12 chromosomes, two less than the expectation from the parental chromosomes. 3. This definite karyotype was observed in all the eight individuals and in the same hybrid obtained separately. 4. It is highly significant, concerning the evolution of the chromosomes, that immediately after hybridization a new definite karyotype is established only by way of mitotic processes. The writers wish to express their sincerest thanks to Prof. Sinotô under whose guidance the present work was carried out. Thanks are due to the Grant in Aid for Fundamental Scientific Research of the Ministry of Education by which this work was partly supported.
An den zu Iridoideae gehörenden 12 Arten and 2 Varietäten wurden die Karyotypen festgestellt; nämlich an 2 Arten von Cypella und Homeria, an 3 Arten von Moraea, an 5 Arten von Iris und an 2 Varietäten von Tigridia. Unter den Karyotypen jeder Arten und Varietäten konnte der Unterschied durch sorgfältige Beobachtung deutlich gemacht werden wenn die Arten oder Varietäten auch die gleiche Chromosomenzahl haben. An einigen Arten der Pflanze nwurde die Verschiedenheit der Chromosomenzahl gegenuber den schon beobachteten gefunden. Iris tectorum hat triploide Chromosomenzahl, die aber aus drei haploiden Sätzen nicht besteht. Zum Schluß möchte ich meinem hochverehrten Lehrer Herrn Prof. Dr. Y. Sinotô, nach dessen wohlwollendem Vorschlag ich these Forschung machte, an dieser Stelle meinen verbindlichsten Dank aussprechen.
The karyotype analysis of Ginkgo biloba L. has been studied in the mitotic cells of young leaf meristems. The basic number (b) is twelve. A haploid chromosome complement in both sexes contains two submedian and ten subterminal chromosomes, of which the longest is submedian and has a trabant, and the eighth is subterminal and trabanted. The. chromosome with tandem trabants is occasionally found. The karyotype formula follows: K(2n)=24(2b)=2tAsm+2Bst+2Csm+8Dst+2tEst+8Fst where t, sm, and st represent trabant-, submedian-, and subterminal chromosomes, respectively. Sticky chromosome bridges in ana- and telophases in mitotic cells have been met with in the young leaf meristem not infrequently. This irregularity was frequent in the young leaf shoots sprouted early in April, and decreased as the date elapsed and diminished at the end of May. It is suggested that these irregularities caused by the special physiological condition are probably due to cellular inclusions-certain organic substances extractable by water.
The action of Streptomycin upon the mitotic cells of Tradescantia paludosa has been studied cytologically. The concentration of the anti-biotic ranged from 25ppm to 1000ppm (parts per million). Every kind of cytological disi-option, comparable to those inducible by x-ray irradiation or the action of mutagenic chemicals, has been observed in contrast to the rather slight cytological disruption heretofore reported. Taking into consideration all the data now available, concerning the effect of Streptomycin upon either microorganisms or higher plants, it seems most likely that the action of Streptomycin upon mitotic cells is to be mutagenic, and is able to induce both minor genie recombinations and major alterations such as translocation or polyploidy.
1) By means of Mallory's triple staining method, it was pointed out that the mantle of the pearl oyster (Pinctada martensii Dunker) contains four kinds of secretory cells, such as mucous cells, cells with large secretory granules, cells having both mucous and large secretory granules, and cells including characteristic brown granules. 2) Rabl's method made it possible to demonstrate total calcium content. 3) In the demonstration of insoluble calcium by means of the production of laque with metalic elements, the author was able to obtain a sufficient result by applying Crétin's method. 4) So far as the relation between calcium content and the morphology of glandular cells is concerned, there is no special gland which is proper to a calcareus function.
1. In the present investigation, cytological studies on the F1 plants, raised from T. durum×S. cereale, T. Spelta×S. cereale and T. vulgare×S. cereale, were carried out in meiosis of PMC-s. 2. In these F1 plants, the number of bivalents at heterotypic metaphase of PMC-s are as given in the following table. 3. In one F1 individual the bivalents were observed up to 11. The 7 bivalents in these 11 bivalents are due to the conjugation between the chromosomes of A and B genomes of Triticum, and the 3 bivalents in the remaining 4 bivalents are originated from the conjugation between the chromosomes of R genome of S. cereale, the-latter case being in accordance with the result of a cytological research by Levan (1942) in the haploid rye plant. The remaining one bivalent will be due to the conjugation between the chromosomes of D genome of Triticum. 4. There exists no homology between the chromosomes of ABD genomes of Triticum and those of the R genome of Secale.
1. The inner structure of the X-chromosome at first metaphase of the grasshopper, Podisma sapporense was described in this paper based on preparations which were obtained by the combined technique of the water-pretreatment procedure and paraffin method. 2. The number of gyres in the chromonema of the X-chromosome was found to be 5.5 exclusive of the kinetochore region. The direction of coiling was seen indefinite, and reversal of coiling was rarely observed. 3. The X-chromosome at first metaphase consists of two chromatids each of which is made up of two half-chromatids. Internally the X-chromosome comprises four chromonemata in its fundamental structure, and each one of the four chromonemata corresponds to a half-chromatid. 4. The kinetochore was found located at one end of each chromatid; it was observed as a tiny oblong or sometimes dumbbell-shaped body which connects with the chromonema by a fine thread. 5. The distal end of the X-chromosome is internally characterized by carrying a tiny compact granule which is similar to the kinetochore in appearance.
With the purpose to study the transformation of the solid azo hepatoma of the rat into an ascites tumor in fluid form, the present experiment was undertaken. The procedure is as follows: The hepatoma tissue was cut fine with sharp scissors. The hashed tissue thus prepared was injected in the peritoneal cavities of some healthy rats. At about one day following treatment, the formation of a hemorrhagic exudation occurred in all specimens treated. The exudation contained a number of inflammatory cells. Intermingled with these inflammatory cells, there were formed many islands of cells due to crowding of tumor cells together with the accumulation of hemorrhagic ascites. The hemorrhagic fluid taken from these animals was injected into the body cavities of seven other rats. In two out of such treated specimens, there occurred again the formation of an exudation in their body cavities. In the peritoneal cavities of these animals there was found a considerable amount of hemorrhagic ascites in which are formed many islands consisting of hepatoma cells. A small amount of the hemorrhagic ascites removed from these specimens was inoculated into the peritoneal cavities of six rats. These specimens produced in each case a typical ascites tumor which contains a number of characteristic tumor cells. The ascites tumor thus induced was called “Ascites hepatoma I”. It is capable of successive transmission by intraperitoneal injection of the tumor ascites. The rat which has received the injection of this tumor dies at 15 to 20 days. In general characters this tumos shows many points of analogy to the Yoshida sarcoma as well as to the MTK-sarcomas.
The kinetic behavior of the mitochondria in the course of cell division was successively traced in fresh grasshopper spermatocytes with the use of a phase-contrast microscope, under both normal and induced abnormal conditions. In every case of either normal or abnormal condition of the chromosomes observed during the period from metaphase to telophase, the mitochondria always showed their characteristic behavior in the course of division, and the cleavage furrow is formed without exception in close connection with the characteristic behavior of the mitochondria. The evidence here presented seems to indicate that the mitochondria play a significant part in the formation of the cleavage furrow in cell division.
The morphological aspects and chromosome pairings of a tetraploid hybrid obtained from the cross between diploid and autotetraploid Oryza sativa were described. Besides its high sterility, the appearance of colour in its awns and its lateness in heading, the hybrid morphologically resembled its male parent, the autotetraploid. Meiosis was irregular; only univalents and bivalents were met with at first meiotic metaphase.