糖蜜草（Melinis minutiflora Beauv．）幼穗分化发育．及花和果实形态的研究

本文对糖密草（ＭｅｌｉｎｉｓｍｉｎｕｔｉｆｌｏｒａＢｅａｕｖ．）的幼穗分化发育及花和果实的形态作了研究,将幼穗分化发育过程划分为以下九个时期：第一苞原基形成期;第一次枝梗原基形成期;第二、三次枝梗原基形成期;小穗及颖花原基形成期;雌、雄蕊原基形成期;花粉母细胞形成期;花粉母细胞减数分裂期;花粉充实期;花粉成熟期。全过程历时约需４２ｄ．从抽穗到颖果成熟约需５０ｄ。糖蜜草的花序为圆锥花序。每花序有可育花２０００—３０００朵．小穗是由小穗轴、内外颖片、不育花外稃和小花构成。小花包括有内外稃各一片、一鳞被、雄蕊三枚和一枚雌蕊,颖果千粒重为９１ｍｇ。     

绵竹花形态结构及雌、雄配子体的发育研究

对绵竹（Bambusa intermedia Hsueh et Yi）花器官的形态结构进行解剖观察,其花序属于无限花序,每个假小穗基部都生有潜伏芽。小花类型为开放型,基本结构包括内、外稃各1枚,浆片3枚,雄蕊6枚,雌蕊1枚,柱头羽毛状三分叉。小花中各结构的发育顺序为外稃→内稃→浆片→雄蕊→雌蕊。小穗中小花的发育顺序是由基部向顶部。子房1室,胚珠倒生,侧膜胎座,双珠被。药壁具4层细胞,有大量的败育情况出现。     

水稻小穗轴维管系统网络结构探讨

对籼型、粳型或其不育系与保持系代表品种小穗解剖观察表明：水稻小穗轴维管系统网络由中央维管束和各分枝维管束复合而成。来自小穗柄的１条大的中央主束和几条边围维管束经数次分枝、联结,不断产生新的分枝维管束进入相应的结构。一般颖片中维管束１－２条,第一稃片中１－３条,第二稃片中１－４条,第二朵退化小花残余结构中０－３条,顶生可孕小花的外稃中５条,内稃中３条,浆片中各２条,雄蕊中各１条,雌蕊中３条,主束与支     

棉花竹花形态与结构研究

棉花竹（Fargesia fungosa）是箭竹属重要经济竹种,有关其花器官的形态与解剖结构研究至今尚无报道。本文通过对棉花竹花器官的形态与解剖结构进行观察和分析,结果显示棉花竹花序为“混合花序”,小穗基部具潜伏芽,由单个叶片形成的“佛焰苞”包裹多枚小穗。小穗单次发生,均长3.05±0.390 cm,每枚小穗具有3~7朵小花,小花均长1.85±0.167 cm,颖片2枚。每朵小花皆具有内、外稃各1片,3枚浆片,雄蕊3枚,雌蕊1枚组成。未成熟花药具有4药室,花药壁由外到内依次为表皮、药室内壁、中层和绒毡层。花药成熟后纵裂散粉。成熟花粉粒为2或3细胞型,且具有1个萌发孔。子房1室,上位,侧膜胎座,倒生胚珠,雌蕊具2分叉羽毛状柱头。花药发育异常,导致出现大量败育现象。     

新小竹花形态结构及雌、雄配子体的发育研究

新小竹(Neomicrocalamus prainii)是一种小型攀援竹类,笋秆两用型竹种。该研究通过形态观察和石蜡切片的方法对新小竹花器官形态及解剖结构特征进行观察与描述,为研究竹类植物的生殖生物学提供新的理论信息。结果显示:(1)新小竹的花序为无限花序,没有小穗柄,成熟小穗平均长度为2.98 cm;每个小穗约有4～6朵小花,其中3～5朵为可育小花,顶端均有1朵不育小花;小穗基部有2～4个苞片;小穗轴每节长约0.52 cm。(2)新小竹的可育小花包括1片内稃、1片外稃、3枚浆片(浆片2大1小,边缘光滑)、6枚雄蕊和1枚雌蕊;雄蕊呈梭型,雌蕊羽毛状柱头三裂。(3)新小竹成熟花粉粒多为二核,具1个萌发孔;花药具有4个药室,花药壁由表皮、药室内壁、中层和绒毡层4层结构组成,绒毡层为腺质型;花药发育过程还存在多种异常情况。(4)新小竹子房一室,侧膜胎座,倒生胚珠,双珠被;大孢子母细胞由1个孢原细胞直接发育而成,合点端1个大孢子分化成为功能大孢子,由功能大孢子经过有丝分裂形成多核胚囊,直至发育成熟。研究表明,新小竹雄配子体存在发育异常现象,但大部分发育正常,其结实率低不仅与内在因素有关,外部环境也可能是导致其结实率低的重要因素。     

狗牙根花序发育过程的形态学观察

对狗牙根(Cynodon dactylon‘C299’)花序发育过程中的形态学变化进行了观察。结果表明,‘C299’花序的整个发育过程可分为8个阶段,即营养生长期、穗轴发生期、苞叶原基分化期、小穗原基分化期、小穗分化期、小花分化期、颖片和内外稃发育期及花药和柱头形成期。其中,穗轴发生期(直立茎上有6~9片叶)是抑制花序形成和决定种子产量的关键时期。     

一个水稻畸形颖壳突变体ah的鉴定及其突变性状的遗传分析

水稻畸形颖壳突变体ah是双胚苗品系W2555中自然突变产生的。该突变体的内外稃畸形,退化;雄蕊雌蕊化,雌蕊败育;浆片同源转化为类内外稃的结构,推测该突变体可能影响B功能基因的正常发育。与野生型相比,突变体的小穗分支稀疏,每级枝梗上颖花数目减少,一般为4～6朵;小穗顶端的颖花经常不能成熟,表现为颖花始终泛白,不能转绿,因此该突变也影响花序分生组织的发育。进一步的研究证明,该突变体的发育受外界环境的影响。突变性状的遗传分析表明,该突变体由单隐性基因控制。     

对小麦顶生小穗的初步研究

1.顶生小穗的护颖具有特殊的形态,第二护颖常为小花外稃状,腋内有时还保留着雌雄蕊或内稃残余。说明其不稳定和可变的本质。2.顶生小穗具特殊的坐落位置,其小穗轴与主穗轴一致。顶生小穗原始体发生在穗生长锥顶端,其下无苞原始体,长成后也无小穗领。其护颖和小花外稃与侧生小穗下的小穗领呈严格连续互生状态。说明其一次轴的渊源。3.顶生小穗护颖腋内可长出小穗,小花也可代之以小穗,护颖和小花外稃有时以苞片的形式保留于新侧生小穗外侧。新顶生小穗的护颖来自小花外稃。说明顶生小穗护颖腋内的退化花芽、外稃腋内的小花与侧生小穗都是花序一次轴上的二次轴分枝。4.顶生小穗产生小穗的变异严格按自下而上的顺序进行,与原侧生小穗有严格的连续性。5.事实证明,顶生小穗是一次轴花序,它属于穗状花序顶端的可变部分。     

水稻的开花

白露节后,我校水稻栽培课外活动小组,在10天时间内,着重观察了水稻的开花习性,在这10天当中,是江西宜春晚稻开花的盛期。我们观察到稻花的构造,在每一小枝梗上,生有小穗,其上有一花,花有外稃(较大)和内稃,内外稃下面有2个护頴,内外稃的内面有雄蕊6个(靠外稃3个,靠内稃3个),雌蕊一个立于中央,其下部有2片浆片。内外稃在未成熟时为绿色,雄蕊淡黄色,雌蕊淡绿色,浆片白色,柱头是羽状二裂,外稃顶端有生芒的,也有不生芒的,内外稃外面都有短刺(图1)。     

千金榆花序及花器官发育

在扫描电镜下首次观察了桦木科鹅耳枥属千金榆花序和花的形态发生过程。千金榆雌花序由多个小聚伞花序螺旋状排列组成;每个小花序原基分化出1枚初级苞片和一团小花序原基分生组织,由小花序原基分生组织分化形成2个花原基和2个次级苞片;每个花原基分化出2个心皮原基,形成1个二心皮雌蕊;次级苞片远轴面发育快于近轴面,呈不均等的联合状;雌蕊基部有1层环状花被原基。雄花序为柔荑状,由多个小聚伞花序螺旋状排列组成;每个小花序原基分化出1枚初级苞片和一团小花序原基分生组织,由小花序原基分生组织分化出3个花原基分区,并分化形成3朵小花,小花无花被,位于两侧的小花分别有2枚雄蕊,位于中央的小花有4枚雄蕊,雄蕊共8枚,稀为10枚,该3朵小花为二歧聚伞状排列,其花基数应为2基数。     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

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Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Arranging the elements of the potassium channel: the T1 domain occludes the cytoplasmic face of the channel

The voltage-gated potassium channel is currently one of the few membrane proteins where functional roles have been mapped onto specific segments of sequence. Although high-resolution structures of the transmembrane portions of three bacterial potassium channels, the tetramerization domain and the cytoplasmic ball are available, their relative spatial arrangement in mammalian channels remains a matter of ongoing debate. Cryo-electron microscopic images of the six transmembrane voltage-gated Kv channel have been reconstructed at up to 18 Å resolution, revealing that the T1 domain tetramerizes and is suspended below the transmembrane segments. However, the resolution of these images is insufficient to reveal the location of the third piece of the puzzle, the inactivating ball domain. We have used the aberrant interactions observed in a series of chimæric channels to establish that an assembled T1 domain restricts access to the cytoplasmic face of the channel, suggesting that the N-terminal ball and chain may be confined in the space between the T1 domain and the transmembrane portion of the channel.     

Separation of the pineal vesicle from the wall of the third ventricle during the post-hatching development of the chicken

Summary According to light- and electron-microscopic observations the pineal organ of the 3-day-old chicken consists of a prominent end vesicle and a tapering parenchymal stalk. During this stage the pineal lumen is in open communication with the third ventricle. However, in the 40-day-old chicken, which still possesses a well-developed end vesicle, the proximal portion of the pineal stalk displays regressive changes leading to local fragmentation. At this stage the pineal stalk is reduced, and the pineal lumen is missing. In 1-year-old chickens the parenchyma of the proximal portion of the stalk is further diminished, and in 3-year-old domestic fowl is completely displaced by bundles of collagenous fibers, only some nerve fibers being present. This post-hatching pineal development may reflect the sequence of changes leading from pineal sense organs to pineal glands.This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science and Culture of Japan     

On the Dependence of the Quadratic Risk of the Classical Predictor and the Prediction-Horizon

When constructing predictors on the basis of the linear model of time series of various indicators often the question arises on the dependence of forecasting accuracy and the changing prediction horizon. The dependency of the quadratic risk of the classical predictor and the time horizon is considered.     

中国植物区系与其它地区区系的联系及其在世界区系中的地位和作用

基于吴征镒将中国全部种子植物３２３８个属的分布区划分为１５个大类型和３４个变型的基础上,简要地讨论了中国植物区系与其它地区区系的联系,以及它在被子植物起源方面的作用。主要论点如下：（１）与热带亚洲区系的联系。这种联系主要通过第７类型（热带亚洲分布）及其５个变型来体现的。本文列举了１０个科,龙脑香料、狭义隐翼科、交让木科、五隔草科、五列木科、肉实树科、心翼果科、八宝树科、兰花蕉科和四数木科,来说明这