No description available.

1. The materials consisted of 20 Salmo salar (salmon parr), 12 Rana teroporaria (frog), 12 Lacerta viridis (Common green lizard), 45 Gallus domesticus (domestic fowl), and 20 Mus norvegious albinus (common white rat). 2. The brains, having been fixed by injection with 10% neutral formol-saline, were carefully dissected out. Some measurements and photographs were made, and the specimens were embedded in paraffin outing down the time of dehydration in the higher grades of alcohol to a minimum and avoiding cedar-wood oil as a clearing agent for reasons which have been given in the text. Three series of serial sections, out at 15?, were prepared from each brain embedded, and were respectively, (a) impregnated with silver by the Bodian Method, (b) stained with, carbol fuohsin and (c) stained with iron haematoxylin. One hundred and two such series were prepared. 3. The following conclusions were reached: (a) The size of the optic lobes, as observed from the surface and relative to the size of the cerebrum, was found to diminish as the vertebrate series of brains was ascended. Estimations of the volume of the optic lobes were, however, not made. (b) It was verified that the superior and the inferior colliculi of the mammals are homologous respectively with the optic tectum and the torus semi-circularis composing the sub mammalian optic lobe. Further, it was found that structurally the optic lobes (in: eluding the ventricles) of the pieces, amphibia and reptilia, and the tectum of the mammalia could be arranged in this order as a series. The optic lobes of the aves were, however, divergent, in that they could not be placed in the series as an intermediate stage between the reptilian and mammalian forms. (c) Throughout the vertebrate series the optic tectum including the superior colliculus of mammals presents a lamination of its constituent cells and fibres. The layers of the representative brains were numbered from without inwards and were compared and correlated with each other using Huber and Crosby's classification of the layers in the reptilian optic tectum as a standard. The lamination of the optic tectum at first increases as the vertebrate series is ascended; it reaches its peak development in the lizard and the bird, and undergoes a reduction again in the mammals. (d) Homologies in the structure of the torus semi-circular is of the lower vertebrates, the nucleus mesencephalicus lateralis pars dorsalis of the aves and the inferior colliculus of the Mammalia were noted. (e) The morphology of the torus longitudinalis, conspicuous in the teleostean fish, was examined. The torus is formed by the fusion in the median plane of two separate processes, from the dorso-medial part of the optic tectum all the layers of which take part in its formation.

No description available.

The research reported in this thesis examines factors that affect the willingness of rats to ingest novel flavour solutions. Emphasis is placed on the memorial processes assumed to underlie the decision as to whether or not a solution is "safe" to drink. Rats exhibit caution (neophobia) in consuming an unfamiliar (target) solution. This unconditional response to novelty habituates as the rat acquires experience with the target solution (provided that ingestion of the target solution has no noxious consequences!). Neophobia to the target solution may be restored, however, if another (distractor) solution is presented during the interval separating pre-exposure to, and testing of, the target solution (Green & Parker, 1975). In Section 1, the phenomena of habituation to an iterated target stimulus and the disruption of this process by a distractor are introduced. Theoretical explanations of the "dishabituation" effect of a distractor stimulus are described and assessed. The possibility of an empirical test of the relative validity of the Robertson and the Wagner hypotheses using the attenuation of flavour neophobia procedure of Green and Parker provided the impetus for the experiments reported in Section 2. In Section 3, attention is drawn to the similarity of the procedure designed to establish habituation and that Intended to establish latent inhibition to a stimulus. A limited review of empirical data is presented testifying to the fact that habituation and latent inhibition are affected similarly by identical parameter manipulations. The Wagner (1976) model views habituation and latent inhibition as the outcome of a common underlying process, Expts. 10a and 10b, therefore, sought to determine whether latent inhibition of a conditioned taste aversion (CTA) to lemon or sucrose solution would be affected by a coffee distractor in a manner consonant with predictions derived from the results of the neophobia experiments reported in Section 2. The distractor, however, had no effect on strength of latent inhibition in either experiment. Expt. 11c demonstrated that it is possible for a distractor (30% vanilla) to disrupt attenuation of neophobia to a target flavour (3% cider vinegar) without affecting latent inhibition to the target flavour, i.e., there is no direct correspondence between measures of habituation and latent inhibition to the same stimulus. In Section 4, the phenomena of overshadowing and potentiation of a CTA are introduced. At least one explanation of potentiation (c.f., Durlach & Rescorla, 1980) stresses the importance of an association between the elements of a compound CS. Rescorla and Furrow (1977) found interstimulus associations were formed more rapidly between similar rather than dissimilar stimuli. Given these results, Expts. 12a and 12b sought to determine whether a single sequential presentation of lemon and coffee (similar solutions) paired with LiCl would result in potentiation of a conditioned aversion to the lemon solution and whether a single sequential presentation of sucrose and coffee (dissimilar solutions) paired with LiCl would result in overshadowing of a conditioned aversion to the sucrose solution. These experimental predictions were confirmed. In Section 5, a potential confound in the neophobia experiments is addressed. Interpretation of attenuated neophobia as a habituation process is defended and alternatives to the Wagner (1976) theory of habituation are considered for their ability to encompass the data reported in Section 2. Only the Wagner model, however, appears able to account for all the data. Nevertheless, some limitations of the model are indicated. Finally, the conditions promoting overshadowing and potentiation of a CTA are discussed.

The homolytic ring fission of strained bicycloalkyl radicals was investigated by E.S.R. spectroscopy. These bicycloalkyl radicals provided examples of cycloalkyl-, cyclopropylmethyl-, and cyclobutylmethyl-type radicals in which the preferred mode, and rate of β-scission could be studied. Three types of compounds were investigated; i.e. (i) bicyclo[n.1.0]alkanes, where n = 3-6; (ii) spiro[2.n]alkanes, where n = 3,4; and (iii) spiro[3.3]heptanes. Observations on the corresponding radicals enabled the influence of; (a) ring size (and consequent ring strain), and (b) the orientation of the SOMO on the rearrangement to be assessed. The series of bicyclo[n.1.0]alk-2-yl radicals, where n = 3-6, were found to undergo β-scission of the outer cyclopropane bond to give the corresponding cycloalkenylmethyl radical. Ring fission was very rapid, and only the rearranged radicals could be detected in the accessible temperature range. In contrast, the first two members of the series (n = 1,2) rearranged by fission of the internal cyclopropane bond to give cycloalkenyl radicals. The conformations of the rearranged cycloalkenylmethyl radicals were determined from the temperature dependance of the β-hydrogen h.f.s., and were interpreted in terms of steric effects. The geometries of the radical species, their enthalpies of activation, and the enthalpies of reaction were calculated by semi-empirical MNDO computations. Photobromination of the n = 3 and n = 4 bicycloalkanes was carried out. The major products were identified and analysed. The main process in each case was homolytic displacement by bromine atoms with consequent fission of the outer cyclopropane bond. This SH2 reaction showed a clear parallel to the β-scission in the series of radicals. However, the change in the mode of fission from internal to outer cyclopropane bond with increasing ring size was less clear cut. Hydrogen abstraction from the spiro[2.n]alkanes gave SFd.ro[2.n]alk-4-yl radicals which ring open in one mode only to give cycloalkenylethyl radicals. The rate of β-scission increased greatly from the n = 2 to the n = 3 to the n = 4 member of the series. With spiro[2.3]hex-4-yl radicals both unrearranged and rearranged radicals were detectable. The Arrhenius parameters for the rearrangement were determined from measurements on the concentrations of the two species. The conformations of the ring opened cycloalkenylethyl radicals were deduced from the temperature dependance of the β-hydrogen h.f.s. The photobromination of spiro[2.3]hexane gave mainly 1-bromo-1-(2-bromoethyl)cyclobutane and 1,1-bis(bromomethyl)-cyclobutane from the SH2 attack of bromine atoms at the cyclopropane n carbon atom. Semi-empirical MNDO calculations were carried out to predict the enthalpies of activation, and the enthalpies of reaction for the rearrangements. Bromine abstraction from 2-bromomethylspiro[3.3]heptane gave rise to a cyclobutylmethyl like radical, namely the spiro-[3.3]heptane-2-methyl, radical. This radical rearranged via β-scission to a 1-(prop-2-enyl)cyclobutylmethyl radical. Both unrearranged and rearranged radicals were detectable. As with spiro[2.3]hex-4-yl radicals the Arrhenius parameters for the rearrangement were determined. The enthalpy of activation, and the enthalpy of reaction were also calculated by semi-empirical MNDO ccmputations. The conformation of the unrearranged radical was determined from the temperature dependance of the β-hydrogen h.f.s. Attempts to generate spiro[3.3]hept-1-yl radicals from spiro[3.3]heptane were unsuccessful due to the failure to prepare spiro[3.3]heptane. The spiro[3.3]hept-2-yl radical was however observed. This radical did not undergo β-scission. With the cyclobutylmethyl-, and cyclopropylmethyl like radicals β-scission was observed to occur in a stereoelectronically allowed manner. Overall this study has confirmed that the major influence in the ring fission of cycloalkylmethyl radicals is the stereoelectronic effect. Thus orbital interaction, through maximised overlap, is a prerequisite to β-scission of both cyclopropylmethyl- and cyclobutylmethyl-like radicals. The study of spiro[2.n]alkanes revealed that ring size may affect the rate of ring fission by way of a conformational effect.

Using a combination of solid-state NMR techniques including Tip measurements, dynamic line shape analyses and 2D EXSY data, a variety of intramolecular motions including rotations of methyl, t-butyl, t-amyl, phenyl, trimethylammonium and trimethylphosphonium groups in a series of quaternary ammonium and phosphonium salts have been investigated. Where possible, activation parameters Ea, △G+/-, △H+/- and △S+/- have been derived. A range of values was recorded, especially for △S+/- which ranged from +75 JK−1 mol−1 for a phenyl group to -57 JK−1 mol−1for a t-butyl group. It was shown that 13p and 31p T1p measurements from CP/MAS spectra can give quantitative information on the kinetics of intramolecular motions that agree with line shape analysis. Recent work using X-ray crystallography has suggested that some derivatives of bicycle [3.3.1] nonane show evidence of conformational equilibria in the solid state. Using 13CP/MAS NMR, 22 derivatives of bicycle [3.3.1] nonane were studied, some at variable temperature. No evidence of conformational equilibria was observed in the chosen compounds. Solid-state NMR has been used to follow the kinetics of ring- chain tautomerism in a bicyclic tetrahydro-1,3-oxazine derivative. This was found to form initially the metastable chain on crystallisation, which then cyclises. The kinetics of the cyclisation were followed and the activation energy for the solid-state reaction was derived. In contrast to this, a related pyrimidine derivative has been found to form initially the metastable ring on cyclisation which quickly ring opens to the chain.

Physiological studies were made of 23 species of red seaweeds (Rhodophyta) and 2 species of green seaweeds (Chlorophyta) in Sicily and at various sites in the British Isles. In Britain, these algae formed part of an "underflora" beneath the canopy of the dominant sublittoral "kelp forest" of Laminaria hyperborea (Phaeophyta). In the Mediterranean, the algae studied formed a turf composed largely of green and red species. In Britain, a standing crop of non-laminarian species of 140g dry weight m-2 was recorded at 5m depth, and approximately half of this at 12m; the crops were about 4 and 12% respectively of the total biomass per m2. At Sicily (Ganzirri, Straits of Messina) a maximum crop of 1360g (dry weight) m-2 was recorded at 15m depth. Radioactive tracer (14C) and dissolved oxygen (Winkler) techniq.ues were developed for use underwater to depths of 60m. Photosynthetic rates measured under agitated incubation conditions were approximately twice the values obtained under static conditions. Rates of photosynthesis measured using the 14C technique were generally high in shallow algae incubated in situ in Britain, e.g. 20 mug C cm-2 h-1 for Porphyra umbilicalis at Om depth; 11 mug C cm-2 h-1 for Rhodymenia palmata, 3m depth. Deeper algae had lower in situ rates, e.g. Delesseria sanguinea, 3.1 mugC cm-2 h-1 and Phycodrys rubens, 1.8 mugC cm-2 h-1, both at 18m depth. At Ganzirri, using the C method, Porphyra umbilicalis attained a rate of 18 mugC cm-2 h-1 at 4.5m and Pseudolithophyllum expansum 4.7 gC cm-2 h-1 at 60m depth. Rates of photosynthesis were strongly reduced by the reduction of irradiance by the water column. Reduction of rates was even more strongly influenced by self-shading in algal stands, Dilsea reaching a photosynthetic efficiency of 8% beneath a L.hyperborea canopy at 4m depth. In general, deep-growing algae were found to be "shade-adapted" (low maximal photosynthetic rates, high-efficiency at low irradiance) and shallow-growing algae were "sun-adapted" but there were notable exceptions. Adaptation occurred within single species. At the deep sites, green algae had photosynthetic rates as high as, or higher than, coexisting red species, suggesting that the red algae had no simple intrinsic photosynthetic advantage conferred by their accessory pigments. Deep specimens of red species exhibited photoinhibition of photosynthesis and photodestruction of pigments when incubated in surface solar irradiance of N 40 J cm-2 PAR. This was noted in such species as Delesseria sanguinea, Phycodrys rubens, Peyssonelia sp., Pseudolithophyllum expansum. Few species studied were below 24-hour compensation point during the summer months and high irradiances of the studies. Few of the deeper algae, however, were operating at or above saturation for any significant length of time. They were thus generally operating at their own maximal efficiencies for most of the time.

No description available.

This thesis traces the development of the Scottish railway system from the horse-drawn waggonways of the eighteenth century to the eve of the railway mania of the mid-1840s. It includes discussion of most aspect, of railway history in the period, but concentrates on the planning and formation of the various companies, the problems and achievements associated with the construction of the railways, and their financial record up to 1844, The first chapter considers the waggonways created between 1722 and 1824, generally by mineral proprietors, for the conveyance of coal either to water transport or to ironworks. From the limited available evidence an attempt is made to analyse their impact on coal traffic, particularly: to the cities of Glasgow and Edinburgh, and to estimate their costs of construction. More detailed examination is then made of the abortive early nineteenth century plans for long distance waggonways not entirely dependent on mineral traffic. In the 1820s the advent of the locomotive, the greater length of most lines, a substantial increase in traffic volumes, and a consequent increase in costs led to greater capital requirements, wider share ownership, and the need for parliamentary authorisation and compulsory powers for land purchase. The result was the coal railways, concentrated principally in north Lanarkshire and for the first time offering a direct challenge to the canals, which are discussed in chapter 2. Chapters 3 and 4 concentrate on the inter-urban lines authorised after 1835 the central belt and in Angus. These lines, influenced by the example of the Liverpool & Manchester, moved away from the earlier concentration on minerals to a more varied freight traffic and in particular to catering for large numbers of passengers. Chapter 3 discussed the projectors of the lines, the problems of promotion up to the time of parliamentary authorisation and, by examination of company subscription contracts, the sources of finance. Chapter 4, based on a detailed analysis of company accounts, examines the wide discrepancies between original estimates and eventual costs by considering the various subsections of constructional expenditure - parliamentary costs, land, engineering, works, rolling stock and so on. Also examined is the record after opening on current account, with reference in particular to the level of working expenditure and to the boom in passenger traffic; comment is also made on difficulties caused by government taxation policy, by Sabbatarian pressures, and by inter-action with road and water transport. The various projects to link Scotland and England by rail are discussed in chapter 5. The obvious desire for a trans-border line was complicated by uncertainties over routes, engineering difficulties, limited traffic prospects, and the common belief that not more than one such line could be made to pay. Even so three lines had been authorised by 1846, and in this chapter the chronological bounds of the study have been slightly extended to include the creation of the Caledonian and the Glasgow Dumfries & Carlisle. The final chapter ties together the main threads of the argument, briefly examines the effect of English influences and the limited economic impact of these early lines, and looks forward to the railway mania.

No description available.