THE TEETH OF HYPOGEOPHIS ROSTRATUS (AMPHIBIA, APODA) AND TOOTH STRUCTURE IN THE AMPHIBIA

The bipartite nature of the tooth has been recently used to demonstrate the close relationship between the three existing groups of Amphibia. However, Considerable doubt has remained as to the composition of the two parts of the tooth and the way in which they are linked.
It order to clearify the position the teeth in Hypogeophis were examined. It is clear that the bulk of the crown and the pedicel is composed of dentine which is produced by a continuous layer of odontoblasts. This layer of cells is also responsible for the formation of the fibrous ring which joins the two portions of the tooth. This ring is regarded as an area where the odontoblasts produce fibres and little or no matrix.     

TRANSFORMATION OF THE NUCLEUS IN MARCHANTIA SPERMATIDS: MORPHOGENESIS

It is proposed that elongation of the nucleus in spermatids of Marchantia results from interaction between its membranous envelope and microtubules of the spermatid's cytoskeleton. The nucleus may be drawn out in two directions along microtubules until forces attracting the nucleus to them are balanced by forces resisting envelope distortion. Condensation of nuclear chromatin into fibrils of uniform diameter and probable shaping of the nucleus by blebbing of its envelope occur together before elongation is complete. The nucleus becomes crescent shaped and it is prolonged distally into a chromatin-free diverticulum. In accord with their distribution along the axis of the nucleus, chromatin fibrils are compacted together forming a cone-like rod of chromatin which narrows anteriorly and extends distally to the tip of the preexisting diverticulum. Elongation and shaping of the nucleus influence the distribution of its chromatin and thus its ultimate morphology. Coiling of the nucleus is related to a reduction of spermatid cytoplasm during maturation.     

STUDIES IN THE HELMINTHOCLADIACEAE. II. TRICHOGLOEOPSIS

Abbott , Isabella A. (Hopkins Marine Station of Stanford U., Pacific Grove, Calif.), and Maxwell S. Doty . Studies in the Helminthocladiaceae. II. Trichogloeopsis . Amer. Jour. Bot. 47(8) : 632–640. Illus. 1960.—A new genus, Trichogloeopsis , in the Helminthocladiaceae of the red algal order Nemalionales is described. Its diagnostic features are the possession of sterile rhizoids produced by the gonimoblast, and the fact that the carpogonial branch is a modified vegetative filament. The type species of the genus is T. hawaiiana from the Hawaiian Islands. Two species of Liagora, L. pedicellata from the Bahamas and L. mucosissima from the Ryukyus, are transferred to the new genus.     

THE TRANSFORMATION OF THE PLASMODIUM GALLINACEUM OOCYST IN AEDES AEGYPTI MOSQUITOES

Sporoblast and sporozoite formation from oocysts of the avian malarial parasite, Plasmodium gallinaceum, after the seventh day of infection in Aedes aegypti mosquitoes offers an interesting example of differentiation involving the appearance and modification of several cellular components. Sporoblast formation is preceded by (a) invaginations of the oocyst capsule into the oocyst cytoplasm, (b) subcapsular vacuolization and cleft formation, (c) the appearance of small tufts of capsule material on the previously noted invaginations, and (d) linear dense areas located just below the oocyst plasma membrane which predetermine the site of emerging sporozoites from the sporoblast. The subcapsular clefts subdivide the once-solid oocyst into sporoblast peninsulae. Within the sporoblast, nuclei migrate from the random distribution seen in the solid oocyst and come to lie at the periphery of the sporoblast just below the linear dense areas noted in the earlier stage. A typical nuclear fiber apparatus occurs in most of the nuclei seen in random sections at this stage although such a fiber apparatus may occasionally be seen in the solid oocyst stage. The nucleus, its associated fiber apparatus, and the overlying dense area appear to induce the onset of sporozoite budding from the sporoblast as well as the formation of the sporozoite pellicular complex and the paired organelle precursor. Several mitochondria are present in each sporozoite, in contrast to the single mitochondrion seen in the merozoites of the erythrocytic and exoerythrocytic stages of avian malaria infection. The paired organelles and associated dense inclusion bodies are formed by condensation of an irregular meshwork of membrane-bound, coarse, dense material. The nature of small, particulate cytoplasmic inclusions is described.     

THE SWELLING OF ISOELECTRIC GELATIN IN WATER : II. KINETICS.

It has been assumed that gelatin consists of a network of an insoluble material enclosing a solution of a more soluble material. The swelling of gelatin is therefore primarily an osmotic phenomena in that the water tends to diffuse in owing to the osmotic pressure of the soluble material. This osmotic pressure is opposed by the elasticity of the insoluble constituent, and equilibrium results when these two pressures are equal. The rate of the entrance of water should then obey Poiseuille''s law, provided the variable terms are expressed as functions of the volume. Equations have been derived in this way which agree quite well with the experimental curves and which predict the proper relation between the size and shape of the block and the rate of swelling. They lead to a value for the rate of flow of water through gelatin which has been checked by direct measurement. The mechanism assumed predicts that at a higher temperature and under conditions such that the water has to pass through collodion before reaching the gelatin, the experiment should follow the same course as that of osmosis discussed previously. This was also found to be the case. The slow secondary increase in swelling is ascribed to fatigue of the elastic properties of the gelatin. The rate of this secondary swelling should therefore be independent of the size of the block, in contrast to the rate of primary swelling which is inversely proportional to the size. It can further be shown that this secondary swelling should be proportional to the square root of the time, and also that with large blocks at higher temperatures the entire swelling should be of this secondary type. These predictions have also been found to be true.     

新伪尾柱虫腹皮层纤毛器微管胞器的形态和形态发生

应用荧光紫杉醇直接荧光标记法显示,腹毛目纤毛虫新伪尾柱虫(Pseudourostyla nova)腹皮层纤毛器微管胞器由口围带、波动膜、额腹横棘毛和左右缘棘毛等纤毛器微管及纤毛器基部附属微管组成.口围带基部含小膜托架及与托架相联系的肋壁微管,其中领部小膜托架间由"Λ"形微管相联接;额腹横棘毛基部含前纵微管束、后纵微管束、横微管束和周围微管束,其微管在不同棘毛基部的发达程度不一;缘棘毛基部含前纵微管束、后纵微管束.同时,对新伪尾柱虫纤毛器微管胞器的形态发生和生理改组过程进行了详细的追踪研究,并对细胞皮层的额腹棘毛定位及组成特征进行了补充报道.此外,发现形态发生末期新纤毛器微管形成时,残存部分老额棘毛、横棘毛和缘棘毛,此后老结构逐渐被吸收.结果表明,新伪尾柱虫的纤毛器基部微管具有其种的特异性,新纤毛器微管分化过程中老结构可能具有定位和物质贡献作用.     

Microtubular protein reaction with nucleotides.

The dissociation constants for GTP and GDP with tubulin were determined to be equal to 1.1 ± 0.4 × 10^?7 M and 1.5 ± .6 × 10^?7 (4°), respectively. A lower limit for the dissociation constant for ATP was established as equal to 6 × 10^?4 M. The equivalent binding of GTP and GDP is not readily consistent with a mechanism in which the role of GTP in microtubule assembly is to bind to the protein to induce a conformation which is able to polymerize. An ATP-induced polymerization of tubulin apparently involves a transphosphorylation reaction in which GTP is formed and mediates the assembly. For this reaction to occur with desalted tubulin trace amounts of GDP are required; in the reaction of 0.1 mM ATP with 22.0 μM tubulin, 0.1 μM GDP induces about 80% as much tubule formation as is seen with 0.1 mM GTP alone.     

Morphogenesis in Schizophyllum commune. II. Effects of Monochromatic Light

The photoinduction of fruiting bodies by light of defined wavelengths was studied in the fungus Schizophyllum commune Fr. Several properties of the induction were established. (1) The exposure-response relationship for induced fruiting was determined for light of 448 nm. (2) The Bunsen-Roscoe Law of Reciprocity was found to hold for the photoinduction of fruiting bodies for the interval 36 to 2000 sec with light of 448 nm. (3) Light of wavelengths from 320 nm to 525 nm induced fruiting bodies. Although the photoreceptor is unknown, it may be a flavin rather than a carotenoid, because light in the near ultraviolet (350 nm-400 nm) was inductive. (4) Neither red light (660 nm) nor far-red light (730 nm) induced fruiting bodies or affected the sensitivity of the fungus toward photoinduction by blue light (448 nm).     

The Morphogenesis of Apple Buds: II. The Development of the Bud

The formation of the terminal resting bud of apple spurs wasstudied on untreated and defoliated spurs by dissection of budscollected at intervals during the season. A distinctive patternof bud development was found in all treatments, the principalfeatures being firstly the steady rate over long periods ofthe season at which successive primordia began or completedbud-scale development, and secondly a change in rate of initiationof bud-scales several weeks after the resting bud had begunto form. Bud-scale initiation was invariably delayed in primordia inthe early period of bud development, when primordia adjacentto the apical meristem were affected directly by the foliage.The rate at which the number of mature bud-scales in the budincreased during the season was not related to the extent offoliar development, but appeared to depend upon the degree towhich the bud, during its early development, was affected bythe foliage. Whilst defoliation of spurs showed that the formation of bud-scaleswas dependent upon an effect of the foliage, no simple relationshipwas found. The number and size of leaves on defoliated spurswas much less than on untreated spurs, but the pattern of buddevelopment was very similar. Since the morphogenetic effectof foliage is known to vary with its age, the constant rateof formation of bud-scales during the season was consideredto be evidence of a second factor in the bud which counteractedvariations in effect of the foliage. A change in rate of increasein number of bud-scales could only occur therefore if the effectivelevel of one of these factors was altered independently of theother. This, it is suggested, is brought about by the accumulationof a further factor in the bud-scales, at a rate determinedduring the early formation of each primordium. From the similaritybetween the effects of these hypothetical factors and thoseof growth-regulating substances extracted from or applied tobuds of fruit trees it is thought that the second factor maybe a gibberellin-like substance, and the bud-scale factor agrowth inhibitor.     

Studies in Morphogenesis of Brassia oleracea L.: II. THE COMPARATIVE MORPHOLOGY OF TYPICAL HEADING-TYPE CABBAGE PLANTS AND NON-HEADING ROGUES

Non-heading rogue plants of January King cabbage have as manyleaves, and as short vegetative axes, as typical heading plants.Leaves of rogues are generally narrower than those of a correspondingage from headed plants sampled in the same crop, and their drymatter content is higher. Rogue plants of January King sampledin the winter had more advanced flower development than headedplants. The significance of these differences for the explanationof the phenomenon of heading is discussed.     

THE COLONIZATION OF DROSOPHILA SUBOBSCURA IN CHILE. II. CLINES IN THE CHROMOSOMAL ARRANGEMENTS

Drosophila subobscura is a Palearctic species that was first detected in the New World in Puerto Montt (Chile) in February 1978. Since that time, it has spread over a broad area and increased in population density. The South American populations exhibit a high level of chromosomal polymorphism: 20 different arrangements exist, distributed among five chromosomes. Chromosomal arrangement heterozygosity varies from 0.55 to 0.61 in the nine populations examined. Incipient clines in the frequencies of the arrangements are appearing; these clines follow the same latitudinal direction as in the Old World. Wing length significantly decreases with latitude, as it does in Europe. The colonization of South America by D. subobscura appears to be a major natural experiment with outcomes that duplicate the distributional patterns—in chromosomal polymorphism and in wing length—observed in the Old World, thereby strongly supporting the adaptive significance of these patterns. The data show a very rapid effect of natural selection promoting genetic differentiation among natural populations.     

STUDIES ON THE ENDOPLASMIC RETICULUM : II. SIMPLE DISPOSITIONS IN CELLS IN SITU

A survey of a large number of different cell types has indicated the presence of a network of membrane-bound cavities (the endoplasmic reticulum) in the cytoplasm of all cell types examined, with the exception of the mature erythrocyte. In its simplest form, encountered in seminal epithelia and in leucocytes, the reticulum consists mainly of interconnected strings of vesicles and appears to be randomly disposed in three dimensions. Local differentiations occur within the endoplasmic reticulum of all the cell types studied. The membrane limiting the cavities of the endoplasmic reticulum appears to be continuous with the cell membrane and the nuclear membranes.     

THE INDIVIDUAL AND TRANSFORMATION OF BRIDEWEALTH IN RURAL NORTH CHINA

Drawing on data collected from longitudinal fieldwork, this article explores how the practice of bridewealth in a north China village has been transformed into a new form of property division within the groom's family and how the bride has replaced her parents as the recipient of bridewealth. At the individual level, this transformation has evolved through a long process during which individual brides and grooms negotiated with their parents over control of bridewealth. A misunderstanding about Western individualism provides village youths with a new ideological tool to justify their relentless extraction of money from their parents. At the level of family life, the changing norm of bridewealth has shaped and in turn has helped to re-shape mate choice, family division, and support for the elderly. These family changes occurred within the context of other social changes at the macro level and are closely linked to the role of the powerful state. While emphasizing the active role of the individual in transforming the practice of bridewealth, an important phenomenon that by and large has been overlooked in most studies of marriage transactions, the article also examines the specific strategies by which individuals exercise their agency, choosing to take advantage of the custom of bridewealth instead of abandoning it when it affords them greater autonomy in mate choice and marriage negotiations.     

HPGMR农垦58s光敏感期叶片中阳离子过氧化物酶的变化

以逐垦５８ｓ水稻为材料,用分光光度法和聚丙烯酰胺凝胶电泳,分析了５８ｓ在１０ｈ／ｄ短日照（５８ｓ－ＳＤ）和自然不育长日照（１４．１２ｈ／ｄ左右,５８ｓ－ＮＤ）条件下,育性转换光敏感期,阳离子过氧化物酶活性同工酶的变化。结果表明,在育性转换期阳离子过氧化物酶活性随幼穗发育时期的推进而升高,在ＮＤ条件下,酶活性升高更快。在所测定的２上时期中,收丙烯酰胺凝胶电泳图谱可以况５８ｓ－ＳＤ和５８ｓ－ＮＤ均有５