Fixation of plant chromosomes: principles, limitations, recent developments
TL;DR: Critical fixation signifies clarification of chromosome morphology to minute details, in which both primary and secondary constriction regions come out extremely pronounced.
About: This article is published in Botanical Review.The article was published on 1956-06-02. It has received 14 citations till now.
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01 Jan 1999
11 citations
TL;DR: The significant features of this procedure are: use of chromosomes in the haploid condition for karyotype analysis, better exaggeration of constrictions for easier interpretation of chromosome types and good spreading in plants with a large chromosome number.
Abstract: Anthers collected between 9 and 10 AM were treated for 1 hr at 26-28 C with a 0.5% solution of colchicine, washed for 2-4 min in water, placed in 0.002 M 8-hydroxyquinoline for 1 hr, washed in water for 10 min and fixed in: methanol, 60 ml; chloroform, 30 ml; distilled water, 20 ml; picric acid, 1 gm and mercuric chloride 1 gm, for 24 hr. After washing they were hydrolysed in 1 N HCl for 15 min at 60 C, stained in leuco basic fuchsin for 30 min, then smeared on a slide in a drop of acetocarmine. The slides were sealed, stored overnight, the paraffin was removed, and the slide passed through a 1:1 mixture of n-butyl alcohol and acetic acid, then through pure n-butyl alcohol and mounted in Canada balsam. The significant features of this procedure are: (1) use of chromosomes in the haploid condition for karyotype analysis, (2) better exaggeration of constrictions for easier interpretation of chromosome types and (3) good spreading in plants with a large chromosome number.
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01 Jan 2004
TL;DR: In this article, the authors investigate whether individuals correctly respond to their employment status and find that subjects over-react to changes in the parameters governing their decision processes, in that the comparative static predictions of the theory are largely confirmed.
Abstract: This paper reports on an experiment that investigates the apparently robust phenomenon of over-sensitivity of consumption to current income. Using a particularly simple formulation, we also investigate whether individuals correctly respond to their employment status. We find that subjects over-react. Our data enables us to investigate where this over-sensitivity originates; we conclude that economic agents differ in their ability to plan ahead and understand the dynamic process determining their employment status. However, agents seem able to respond appropriately to changes in the parameters governing their decision processes, in that the comparative static predictions of the theory are largely confirmed. A repeatedly observed phenomenon in the empirical literature on the behaviour of consumption is its over-sensitivity (relative to that prescribed by the relevant theory) to current income. We provide here an experimental investigation of this phenomenon, taking advantage of the experimental method to eliminate factors that are not of interest and concentrate attention on those that are. In particular we deliberately adopt a simple model in which income in any period can take just one of two values. We interpret these two values as corresponding to states of employment and unemployment, and we additionally assume that transition between these two states is governed by a first-order Markov process. This formulation represents an empirically relevant advance on previous experimental work and enables us to discover whether individuals react appropriately to their employment status - or whether they over-respond, as the non-experimental
592 citations
TL;DR: A number of investigation have been published in which attempts are made to correlate the chemical or physical properties of substances with the intensity of their toxic action as mentioned in this paper, where the experiments consisted in the determination of the molar concentrations of the compounds which produced equi-toxic on a selected organism.
Abstract: A number of investigation have been published in which attempts are made to correlate the chemical or physical properties of substances with the intensity of their toxic action. Among these may be instanced the work of Moore (1917) on the toxicity of fumigants towards insects, the extensive work of Tattersfield and his collaborators on contact insecticides and fumigants (Tattersfield and others 1920, 1925, 1926, 1927), the bacteriological investigations of Tilley ans Schaffer (1926, 1928) and others (Coulthard, Marshall and Pyman 1930; Dohme, Cox and Millar 1926; Klatman, Gatyas and Shternov 1931), work on fungicides (Morris and Stirk 1932; Stiles and Rees 1935). In each of the investigations just quoted a more or less wide range of chemical compounds was examined. The experiments consisted in the determination of the molar concentrations of the compounds which produced equi-toxic on a selected organism. The toxicities of the compounds studied were then usually assumed to be inversely proportional to the values of these equi-toxic concentrations.
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525 citations