A case of failure of cytokinesis in the anthers of maize during premeiotic and meiotic divisions is described. The failure of cytoplasmic division has no evident effect on the course of the nuclear division. The microsporocytes in which the cytoplasm falls to divide develop into multinueleate spores. The size of these spores is roughly proportional to the number of nuclei present.
Meiosis in male plants of Xanthorrhiza apiifolia L'Her is strictly regular and gives no indication of any abnormality or inequality among the chromosomes which might be interpreted as a sex chromosome complex. No diagnostic hybrid characteristics were found. This bears out the author's prediction and adds another case which is cited in support of the opinion that so-called sex chromosomes will not be found in monotypic species because recent hybridization has not been possible in such species. The chromosome number appears to be n-15. Meiosis in Chamaelirium luteum L. is also quite normal, without any indication that a sex chromosome complex is present. Little evidence was found for recent hybridization of the species. The chromosome number was determined as n-12. The origin of the meiotic chromosomes was studied in Smilax herbacea L., as a result of which the mechanism of active pairing or synapsis is questioned. The meiotic chromosomes seem to arise from a fundamentally continuous spireme which splits longitudinally and later becomes segmented into the haploid number of chromosomes. Eight of the meiotic chromosomes are associated during diakinesis in groups of two each. The chromosome number has been determined as n-13. Meiosis is normal with no trace of diagnostic hybrid characteristics.
1) Drosophila montium is one of the tropical species distributed widely in the Eastern Hemisphere: Africa, Formosa, Java, India, Samoa, Sumatra and southern regions of Japan and China. 2) Two races, A and B, may be distinguished in this species by the difference in chromosome complex, The oogonial metaphase plate includes four pairs of chromosomes, namely, two large V-shaped pairs, a rod-shaped pair (X's) and a pair of small chromosomes, which are V-shaped in Race A and rod-shaped in Race B. In the male, one of the rod-shaped X's is replaced by a small V-shaped Y. In the salivary gland nucleus, six strands radiate from the chromocenter. One of these is much shorter than others and is attached to the chromocenter with both ends like a ring. This apparently corresponds with the short rod and small V found in the metaphase complex. 3) Thirty mutants have been discovered, of which twenty-five are assigned to three linkage groups. The mutants are described briefly. 4) Percentages of spontaneous non-disjunctions and of those obtained by X-ray treatment are given.
(1) Meiosis is described in three diploid and one aneuploid species of Calceolaria. The diploids are C. clibrani (2n=18), C. dentata (2n=18) and C. Banksii (2n=18). The aneuploid species, C. mexicana, has 2n=60. (2) In the diploids, one bivalent is attached to the nucleolus at diplotene and diakinesis, while two bivalents are attached to the nucleolus at zygotene and diakinesis in C. mexicana. (3) At diplotene in the diploids, interstitial chiasmata persist in 35% of the cases but are terminalised at metaphase. Multivalents are rare. In the aneuploid species associations of chromosomes ranging from trivalents to groups of eight are described. Rings and chains of four and six chromosomes were also found. (4) An analysis of secondary association in the diploids at Metaphase I and II shows a maximum grouping of 3 (2)+1 (3). The diploid number 2n=18 is, therefore, considered to have been derived from the basic number 4, indicating allopolyploidy. (5) In the diploids the presence of inverted segments is indicated by the formation of chromatin bridges at Anaphase I. (6) The nature and significance of ring formations in the aneuploid species, the value of structural changes in evolution and the origin of the aneuploid species have been discussed.
1. Spiralized chromonemata present different configurations. The configurations can be classified into two general types, the spiral configuration and the twisted configuration. 2. These configurations are mutually transformable from one to the other. These changes are experimentally demonstrated in the resting nucleus. 3. In the twisted configuration, the nucleus shows a diffuse structure, while in the spiral configuration it presents an aggregate structure, the chromosome territories being perceptible. 4. When staminate hairs are observed in water medium, the prophasic nucleus is transformed directly into the resting nucleus without passing metaphase and anaphase, an “abbreviated mitosis” which is comparable with the endomitosis. It is pointed out that in one mitosis the chromosome splitting never takes place twice, but that it only appears to do so, when one of the two successive mitoses is an “abbreviated” one. 5. From the fact of the spiralized chromonemata presenting different configurations, the problems of 1) the anaphasic or telophasic split, 2) the minor spirals, 3) the fine structure of the nucleus in connection with the problem of the chromonema number in chromosomes, 4) the type of the chromonema spirals, and 5) the optical sign of chromosomes are discussed.
Two problems in interpretation of meiosis were noticed in a study of meiotic chromosomes of Tulipa and Rhoeo. The first is as follows: The prophase nuclei of Tulipa is a dense tangle of threads. Invariably and smoothly the tangle resolves itself into bivalents and trivalents by metaphase. The problem arises, how is such a pairing mechanically possible? The second problem is as follows: The metaphase chromosomes of Rhoeo are linked to each other end to end. Each chromosome is composed of two closely fitting spiral chromatids. It is improbable that the terminal attachments are due to terminalised chiasmata. An alternative solution is wanted. The problem arises only if (i) the facts are correct (ii) if the chromosomes retain their identity throughout the division. (i) is corroborated by other workers' publications and (ii) is an incontrovertible assumption. It is suggested that both the problems have a common solution. Possibly a certain arrangement of chromosomes in the premeiotic telophase facilitates the prophase pairing in Tulipa and originate metaphase figures in Rhoeo.
1. Remarkable cytoplasmic striation pattern is found in the epithelium-cells of yolk-sac membrane and of embryonic body of Oryzias latipes, especially of its fins. 2. The striation pattern is composed of several sets of parallel striations that are arranged in mosaic to every directions. The peripheral one or two striations are, however, arranged parallel to the border of cell, while there is none of the striation that is arranged parallel to the border of nucleus. The parallel striations are about one micron apart from one another. 3. Each striation is made up of minute cytoplasmic particles closely arranged in a line. 4. The striations, however, are unstainable with usual cytoplasmic stains such as eosin and acid fuchsin. 5. The first indication of the striations appears in the epithelium-cells of yolk-sac membrane of 13-somite embryos. At this stage the minute cytoplasmic particles, which hithertofore distributed uniformly in the cytosome, come to be arranged closely in a line, and then the pieces of striation thus formed become continuous and finally establish the striation pattern. The complete striation pattern is found in the epithelium-cells of yolk-sac membrane of the third day embryos. 6. No correlation between the striation pattern and the rythmic contraction of yolk-sphere was found.
The conception of the basic number of chromosomes has been established by the studies made on the chromosome numbers during the last four decades, and a basic number and morphology of the chromosomes composing it have been investigated by the method of karyotype analysis. We propose applying the term basikaryotype to such a chromosome type which is specific to individuals or groups, corresponding in number to the basic number, and viewed from the stand-point of their morphology. The chromosome behavior in meiosis has to be observed in order to pursue the investigation of the phylogenetic relation of the basikaryotypes. The criterion of the homology of chromosomes is assumed to be the pairing of the chromosomes. By this method the existente of those karyotype alterations which were either expected to have occurred or are not capable of being distinguished by the karyotype analysis may be established on karyogenetical grounds. This method is here called a basikaryotype analysis. Comparing the basikaryotype analysis with the genome analysis, the former originated in the karyotype, while the latter started from hybridization as a premise. With the recent advances in the study of chromosome morphology the conception of the genome has come to take the karyotypes into consideration, and accordingly the new stand-point has been developed to facilitate discussion of the genetical connection of individuals or groups based upon the karyotype. The karyotype analysis is different from the genome analysis in that the former enables one to presume the relationship between the forms which can not be hybridized with each other, while it further enables determination of the basikaryotypes. The basikaryotypes may be detected in the forms in which the karyotype analysis was carried out. Some examples have been given (p. 533). The homology of the basikaryotypes may be traced by the method of basikaryotype analysis here proposed. An example of this method in the case of Aloinae was described (p. 534).
1. Unter der Reizwirkung von 10% iger Rohrzuckerlösung wird bei einzelnen Zellen auch der Zellkern unter Gestaltveränderungen mit wechselnder Geschwindigkeit durch die Protoplasmaströmung mitbewegt. 2. Diese Kernrotation beginnt je nach den Umweltbedingungen (Licht, Temperatur, Sauerstoffgehalt etc.) nach verschieden langer Zeit, aber in diesem Falle am 4. Tage nach Beginn der Einwirkung der Zuckerlösung, und dauert ca. 10 Tage an. 3. In einigen Fällen wurde beobachtet, daß die Protoplasmaströmung noch fortdauerte, als der Kern bereits abgestorben zu sein schien. 4. Bei Wiederbenässung von ausgetrocknetem Hydrilla-material tritt in einem Teil der noch lebenden Zellen Umkehrung der Rotationsrichtung ein. 5. In Wasserpräparaten von Hydrilla-blättern, welche mehrere Tage in der Feuchtkammer aufbewahrt worden waren, ging die rotierende Bewegung zeitweise in eine penduläre über. Auch andere Abweichungen von der Normalströmung waren zu beobachten. Zum Schlusse möchte ich noch meinen verehrten Lehrern, den Herren Ehrenprofessor FUJII und Prof. NAKANO der Kaiserlichen Universität Tokyo für ihre gütige Anregung bei dieser Arbeit meinen verbindlichsten Dank aussprechen. Ebenso möchte ich der Japanischen Gesellschaft zur Förderung der Zytologie für ihre finanzielle Unterstützung meinen besten Dank aussprechen.
1. Remarkable cases of the extrusion of a nucleolus in toto from the germinal vesicle into the cytosome of ovarian primary oocytes of Holothuria monacaria were studied cytologically, and all stages of the process were traced. 2. Primary oocyte of this species has one chromatin nucleolus, which grows as large as about 7.5 microns in diameter, becomes vacuolized and finally is extruded from the germinal vesicle when it has attained a size of about 35.5 microns in diameter. A newly formed young nucleolus is found growing in the germinal vesicle when an old one is extruded. 3. The extrusion of a nucleolus takes place successively several times in the growing oocytes. 4. The nucleolus that is about to be discharged contains several vacuoles, and comes to lie close to the membrane of the germinal vesicle which now becomes slightly shriveled. 5. That part of the membrane where an extruding nucleolus attaches comes to be dented outward, and then becomes a pocket containing the nucleolus, protruding into the cytosome. 6. After the pocket containing the nucleolus has been protruded enough into the cytosome, a new membrane is formed covering the mouth of the pocket. 7. Vacuolization of the nucleolus becomes more pronounced after it has been discharged into the cytosome, and then it becomes a large, amorphous mass which stains with acidic dyes.
1. In a race of Papaver somniferum are found 11 bivalents in its diaphase of the PMC, which show the kinds of association as 6 rings, 2 side by side union or, rarely, 2 open rings, 1 end to end union, 1 small ring and 1 largest side by side Union or open ring. While in another race there were found only ring or open ring configurations instead of side by side or end to end unions. 2. There were observed in the former very loose associations “bivalents-associations, ” between 2 pairs of ring bivalents or one pair of side by side bivalents, and also between a ring and an end to end bivalent. In the latter race 4 associations of ring bivalents were found. 3. P. somniferum is an amphitriploid, which has probably been derived as follows: an interspecific hybrid is raised between 2 species, one having 4 chromosomes and the other 3 chromosomes as their haploid complements, then the chromosome sets were doubled causing an amphidiploid, namely 2(4+3)=2(7). This amphidiploid is crossed with a plant which is closely related to one parent having 4 haploid chromosomes, then the whole sets are doubled again, namely (3+4)2=2(7), and then 2(7+4)=2(11). 4. The association or pairing of the two bivalents, “the bivalents-association” was discussed. The writer's hearty thanks are due to Prof. K. Fujii for his kind advice in the course of the investigation. The expence of carrying out the present work was partly defrayed out of a grant from the Japan Society for the Promotion of Scientific Research, to which I tender my thanks.
1) Many meiotic chromosome numbers in the Papaveraceae have been counted. 2) Pteridophyllum is probably descended from a very remote ancestor of Chelidonioideae and should be put in the new family Pteriodophyllaceae. 3) In the Papaveraceae there are two series, one of which, the Corydalo-Hypecoideae, having the basic chromosome number 4 and the other, Chelidonioideae the basic number 3. These two series are independent, but finally unite in Papaveroideae (e.g. Roemeria). There are two kinds of Roemeria: one with the basic number 3 and the other with 3 and 4, thus showing that Roemeria is karyologically a heterogenous genus. 4) Glaucium which has been classified by Fedde with Papavereae, should be grouped with Chelidoneae (the writer's Chelidonioideae) as it is quite different karyologically from other genera in Papavereae. 5) We conclude from the present studies that the following genera have been produced by crossing between plants of Corydaloideae and Chelidonioideae, but their crossing occurred early in the history of development of the family, and we are at present not in a position to trace the exact chromosomal history. *Hunnemannia 7=(4+3)………Corydaloideae (Corydalis, Dicentra or allied species)×Eschscholtzia Bocconia Macleaya 10=(4+3+3)……Corydaloideae (Corydalis, Dicentra or allied spedies)×Chelidonium Fumaria (Fumarioideae) 7=(4+3)………Corydalis or allied species×Glaucium Papaveroideae 7=(4+3) 11=(4+4+3)……Corydaloideae×Chelidonioideae 6) Papaver can be said to be the most highly developed genus among the Papaveraceae, both for anatomical and karyological reasons. 7) Fedde is of the opinion that Fumarioideae (Fumarioideae and Corydaloideae of the present scheme) is the youngest in this family, but as stated before, Fumaria, having a different number of chromosomes from other genera in Fumarioideae (the writer's Corydaloideae), seems to be derived from a genetic connection of Corydalis and Glaucium, as Fumaria and Glaucium have fumaric acid in common. The writer, therefore, believes that Fumaria is situated between Roemeria and Corydalis, having branched out from the latter. Other genera of Fumarioideae (the writer's Corydaloideae) also should be placed before the Papavereae (the writer's Papaveroideae) because of their having the basic number 4. 8) Argemone, although it has fewer species as compared with Papaver, is the most advanced genus in America, while Papaver has become the most advanced genus in Europe and Asia Minor, having about 90 species. In conclusion I desire to express my best thanks to Hon. Prof. Fujii and Prof. Nakai, the director of the Botanical Institute of the Tokyo Imp. University for much valuable advice and the great interest they have shown in my work, and also to express my sincere appreciation of the help and encouragement I have received from Prof. Sinotô and Dr. Yasui during the course of the present work.
1. In the cell of Allium cepa exposed to ultraviolet rays appear such features as cytoplasmic particles and tonoplast plasmolysis both of which mean the disorganization of the cytoplasm, when it is plasmolyzed. All these features which are caused in various kinds of plasmolyticum, indicate the increase of the adhesion between the cytoplasm and the cell membrane. 2. Various features of plasmolysis in the exposed cell can be explained by an assumption of the competition between the cohesion of the cytoplasm and its increased adhesion to the cell membrane. 3. The ions or molecules which are believed to penetrate easily into the cytoplasm, facilitate the destructive process, for instance tonoplast plasmolysis, in the plasmolysis of the exposed cell, when their salts are used as plasmolytica. 4. Al-ion which acts further to raise the adhesion in the exposed cell, restrains the sudden separation of the cytoplasm from the cell membrane in the course of plasmolysis. This action serves more or less advantageously to protect the cytoplasm from the disorganization. A part of the present study has been carried out at the Laboratory of Plant Physiology of Prof. T. Sakamura, Sapporo, to whom the writer wishes to acknowledge his sintere gratitude for granting him the facilities of the laboratory. The writer wishes to express his sintere thanks also to Dr. T. Hori, Professor of Physics, Sapporo, for his kind help in using the physical apparatus. The writer expresses his thanks equally to the Japan Society for the Advancement of Cytology, by the grant from which this work was supported.