MORPHOLOGY OF MARSILEA VESTITA. III. MORPHOGENESIS OF THE LEAVES OF ETIOLATED PLANTS

The laminae of etiolated Marsilea vestita leaves develop by means of marginal meristems. Unlike light-grown plants, the form of the etiolated plant is not affected by growth on a solid medium. All of the young leaves isolated from light-grown submerged plants will elongate in darkness. The smallest, etiolated, uncoiled leaves develop into land leaves when they are placed in light, and this development occurs regardless of whether the leaves remain on the plant or are isolated on nutrient agar. Only these smallest leaves (2.3 mm average length) are actually capable of being converted from a submerged leaf form to a land leaf form by darkness.     

滇丹参注射液对兔血小板功能的影响

观察云南产滇丹参对血小板聚集功能的影响.方法采用Bom氏比浊法,测定滇丹参体内、体外对抗ADP、PAF、AA诱导的兔血小板聚集的作用.体外每种药物浓度分别为40 g/L、20 g/L、10 g/L、5 g/L、2.5 g/L,体内实验分为7组,即生理盐水组、两种丹参低中高剂量组分别为5 g/kg、10 g/kg、20 g/kg,每组6只.结果与对照组相比,滇丹参体外显著抑制ADP、AA诱导的血小板聚集,抑制效应呈浓度-效应关系(P＜0.05,0.01),IC50为33.7 g/L(ADP)、18.1 g/L(AA).滇丹参也显著抑制PAF诱导的血小板聚集,其最大抑制率为36.8%;体内实验结果显示,滇丹参在高剂量时可显著抑制ADP、PAF和AA诱导的血小板聚集(P＜0.05,0.01),且均具有剂量依赖性.滇丹参在药后20 min开始显效,40 min达到最大抑制作用,抑制率分别为95.6%(ADP)、91.5%(PAF)和88.5%(AA).结论以上结果表明,滇丹参体外、体内显著抑制血小板聚集,且其抗血小板聚集作用优于丹参,为进一步开发和利用滇丹参提供了依据.     

羌活挥发油成分分析

从羌活、宽叶羌活的根茎及根中提取了挥发油,用气相色谱-质谱联用法分析挥发油的化学成分,共鉴定了136个成分(羌活78个成分、宽叶羌活58个成分),用气相色谱法测定了挥发油各成分的相对百分含量,其鉴定率分别达到94.90％和91.41％。     

獐牙菜属植物的研究概况

本文对龙胆科獐牙菜属植物的化学和生理活性研究进行了概略的回顾。迄今为止,约有40种獐牙菜属植物有文献报道。从这些植物中已分离出100多种不同类型的化合物,包括(口山)哃、黄酮、甙类、萜类及少部分内酯、生物碱和有机酸类化合物。这些化合物有多种生理活性,如:镇静、抗结核菌、强壮、退热、轻泻、肝保护、抗惊厥、增压及治疗胃病和心血管疾病等。还可制成各种制剂用于生发、护肤、驱虫等。     

牛尾蒿两变种精油的化学成分

本文以气相色谱质谱计算机联用的方法分析了牛尾蒿原变种Artemisia dubia var. dubia及无毛变种B A. dubia var. subdigitata精油化学成分,共鉴定出82种化合物,其中萜类50种,芳香类12种,脂肪族类20种。经比较研究表明,这两变种的精油中有39种化合物(27 种萜类,5种芳香类和7种脂肪族类化合物)相同,而它们的差别在于牛尾蒿无毛变种中二环、三环倍半萜、芳香类及脂肪族类化合物的类型比原变种多。从精油的萜类化学组成特点来看,这两个变种的萜类化合物环化程度比蒿亚属植物高,而与龙蒿亚属植物相近。因此,这两个变种归属于龙蒿亚属较合适。     

PHOTOCONTROL OF THE ORIENTATION OF CELL DIVISION IN ADIANTUM. III. EFFECTS OF METABOLIC INHIBITORS

5-Fluorouracil, 8-azaguanine and ethionine were tested on the orientation of cell division to see whether the two-dimensional development of the fern Adiantum gametophytes was due to newly synthesized protein(s). Using the system in which the orientation of cell division was controlled experimentally by sequential treatment with red light, white light and darkness and by the direction of irradiation, all the inhibitors decreased the rates of cell elongation and cell division of the gametophytes, but did not specifically affect the two-dimensional differentiation at all.     

THE FERTILE SPIKE OF OPHIOGLOSSUM PETIOLATUM. I. MECHANISM OF ELONGATION

The frond of Ophioglossum consists of a sterile segment and a fertile segment or spike. An investigation of fertile spike elongation reveals that growth of the spike proceeds by activity of an intercalary meristem located in the most distal region of the peduncle subtending the sporangial area. Anatomical comparisons of all regions of developing spikes, counts of mitotic figures along the length of spikes of various ages, determination of cell lengths of peduncle ground parenchyma cells, and historadioautography of spikes treated with H³-thymidine confirms the presence in the apical portion of the peduncle of a region of frequently dividing cells intercalated between two regions of more mature tissues. Marking experiments indicate that the petiole of the sterile segment of the frond elongates in a similar fashion. Although this type of intercalary meristem is rather common in angiosperm flower scapes and peduncles, this is the first detailed analysis of this type of growth in a pteridophyte genus.     

CELLULAR SLIME MOLDS OF SWITZERLAND. I. DESCRIPTION OF NEW SPECIES

During the study of the distribution of cellular slime molds in Swiss forest soils, three new species were isolated and studied in culture, namely, Dictyostelium fasciculatum, Dictyostelium polycarpum and Polysphondylium filamentosum. The first is cosmopolitan, the latter two are known only from Switzerland. Dictyostelium polycarpum is a very delicate species and is the first species reported which is restricted to a high altitude environment. It is characterized by a coremiform habit, reminiscent of D. polycephalum, and relatively long reniform spores. Dictyostelium fasciculatum is a larger species which resembles D. mucoroides in gross morphology but is much closer to Polysphondylium in its life cycle pattern and behavior. Polysphondylium filamentosum is only the third well-defined species of the genus to be described. It produces filamentose principal and lateral axes. Optimum temperature for all three is around 20 C, somewhat below that of most other species in the family.     

MOVEMENT OF EELWORMS.: IV. THE INFLUENCE OF WATER PERCOLATION

A study was made of the relationship between rate of flow of water through sands of different particle size and the downward velocity of eelworms of various lengths and activities. The relationship between rate of flow of water and velocity of eelworms is not linear. For rates of flow less than about 500 cm./hr. the velocity of the eelworms relative to the velocity of water is greater than for flow rates greater than about 500 cm./hr. For rates of flow greater than 500 cm./hr. an equation is derived which relates velocity of eelworms, rate of water flow, length of eelworms and pore diameter in the sand. The following facts were established: the velocity of the eelworms increases as pore diameter increases; the velocity approaches zero when the eelworms' length exceeds four times the pore diameter; the relationship between velocity of eelworm and velocity of water is independent of the eelworms' own activity; the equation of eelworm movement is valid for both continuous and discontinuous saturated flow. With flow rates less than about 500 cm./hr., the velocity of the eelworms increases as the eelworms' activity increases and eelworms appear to pass through smaller pores than at high flow rates. Dead or inactive eelworms do not progress very far in sand even at high flow rates and observations suggest that slight flexing movements of the eelworm body is essential for passage.