Science Collected Works - Theses

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The chemistry of the ethylene sulphides and some related topics

Culvenor, C. C. J (University of Melbourne, 1948)
Partition chromatography and its applications

Overell, B. T. (University of Melbourne, 1949)
Some physico-chemical aspects of naturally occurring pigments

Scutt, Philip Buckley (University of Melbourne, 1948)
Bases of mathematical theories of plasticity

Robson, R. A. (University of Melbourne, 1951)
Contributions to the stratigraphy and palaeontology of the Silurian and Devonian of Gippsland

Talent, John A (University of Melbourne, 1959)
Aspects of the water relations of leaves of eucalyptus globulus

Gaff, Donald Frederick. (University of Melbourne, 1959)

Although it is generally recognised that water is one of the main limiting factors in the development of vegetation in Australia, comparatively little physiological work has been done on the water economy of native plants. Ibis is particularly true of the water relations of trees; yet, due chiefly to the scarcity of water in extensive areas of Australia, the proportion under forest is the smallest for any of the continents, except Antarctica. A large proportion of the published work on ecological aspects of plant water relations has been concerned with determinations of the osmotic pressure of the cell sap, although values of osmotic pressure give no indication of the ability of plant tissues to take up water. Ibis ability is measured by the suction pressure of the tissue. Owing to the difficulty involved in its determination, suction pressure has been measured comparatively rarely in physiological and ecological studies. Most of the work included in this thesis consists of investigations relevant to the suction pressure and water deficit of leaf tissue. Juvenile leaves of Eucalyptus globulus Labill. were used as a source of material in the experiments which will be described. As characteristically Australian trees, the eucalypts are a natural choice for study. This particular species (blue gum) is native to arena of south-east Australia, but it is cultivated widely in other countries, so that material is available to many research workers overseas. In addition, saplings of E. globulus had been planted in a garden at the rear of the Botany Department in Melbourne in 1954, and these provided a good supply of leaves throughout the course of the Investigations detailed below. Much of the work on the water relations of plants ms been concerned with the absorption of water, the ascent of sap, and transpiration. Transpiration, its measurement, and the factors affecting it, have received a particularly large amount of attention. The balance between water uptake and water loss by leaves, however, has not been studied very extensively. investigation of this facet of plant water relations was hampered for a long time by the lack of a suitable common denominator upon which to express either the water content or the water deficit of a tissue. Weatherley (1930), made a critical Investigation of the relative merits of tissue dry weight, cellulose content, and protein content, as possible denominators. He found that, owing to marked seasonal trends, these quantities were unsuitable. In experiments on the uptake of water by floating leaf discs, Weatherley found that water was taken up rapidly at first, but that this was followed by a slow steady uptake of water. Weatherley interpreted the initial rapid uptake as due to the elimination of the water deficit of the tissue. The subsequent slow uptake was attributed to growth. On the basis of these observations, Weatherley developed the concept of "relative turgidity", which he defined as the ratio of the amount of water present in a quantity of tissue when sampled, compared with the amount present in the same quantity of tissue when fully turgid. This ratio has the advantage that it does not include a dry weight component and seasonal variations introduced by the use of this term are avoided. In addition, the determination of relative turgidity is comparatively simple, as it requires only three weighings. No work involving these newer methods of expression of water content has yet been published on species of Eucalyptus and one of the objects of this thesis is to investigate the methods of measuring relative turgidity (and other, related functions of plant cells), and the importance of variations in the water content of the leaves of Eucalyptus globulus.
Studies on Gibberellins in relation to higher plants

McComb, A. J. (Arthur J.) (University of Melbourne, 1959)
A study of factors governing the mass economy of Antarctica

Mellor, Malcolm. (University of Melbourne, 1959)

The investigations which have gradually revealed to us the nature and workings of the great ice cap of Antarctica were initiated by explorers of the nineteenth century who determined the broad outlines of the continent. At the beginning of the present century the first land-based expeditions enabled scientists to describe the glacial processes and even undertake some measurements. In 1902 Drygalski measured the movement of the glacier ice at Gaussberg, and precipitation measurements were made at Snow Hill Island by Nordenskjold's Swedish expedition in the same year. During Shackleton's expedition of 1907-19 David and Priestley made glaciological observations and during Scott�s last expedition, 1910-13, Wright and Priestley undertook anew and ice studies which led to the publication in 1922 of their classic 1 book on glaciology. Mawson's Australasian Antarctic Expedition, 1911-14, made glaciological studies, and for the first time in Antarctica an attempt was made to measure the amount of snow blown off the ice cap and out to sea. Between the two World Wars there was little scientific investigation of the ice cap, apart from the work done by Byrd's expedition in 1939-41. There was, however, an important step forward when systematic aerial photography was introduced to Antarctica by Lars Christensen in 1936-37 and Ritscher in 1939. After the Second World War, in 1947. Byrd made an intensive survey of a large part of Antarctica and the huge collection of air photographs secured during this operation gave an overall integrated picture of the ice cap and its physical features. In this post-war period the chain of bases first established in 1943-44 by the Falkland Islands Dependencies Survey was extended, but their outlying situation on the Graham Land peninsula was unsuited to studies of the main ice cap. From 1950 to 1952 the Norwegian-British-Swedish Antarctic Expedition worked in Dronning Maud Land. This expedition was of considerable significance, since it established the principle of close international co-operation and also went into the field with a scientific programme already planned in detail with the aid of air photographs. The expedition used mechanical transport with success and mane the first seismic ice depth measurements on the inland ice. The well executed field work has been followed up by the publication of excellent scientific reports. In 1950 Expeditions Polaires Fran�aises set up a base, Port Martin, on the coast of Terre Ad�lie and this base was occupied for two years before being destroyed by fire. The observations mane in Terre Ad�lie provided the material for an important work on glaciology by Loewe (1956), as well as for a number of shorter papers. A small French base was maintained at Pointe Geologie in 1952, but in 1953 France temporarily withdrew from Antarctica. In 1954 the Australian national Antarctic Research Expeditions, under the direction of Mr. P.G.Law, set up a permanent Antarctic base, Mawson, on the coast of MacRobertson Land. During the first year of occupation measurements of accumulation and ablation were initiated by R. Dovers and firn temperatures were measured on the ice cap. In the following two years observations were extended to include measurements of ice movement, the work being carried out by P. Crohn. The International Geophysical Year of 1957-58, a development from the Polar Years of 1882-83 and 1932-33, called for the setting up of many Antarctic bases by different nations (see map 1) and for a detailed study of glaciology. For the first time simultaneous measurements were to be made in many different parts of the continent and improved means of transportation would permit wide areas to be covered by each expedition. In 1956 the author joined the Australian National Research Expeditions as glaciologist and in 1957 wintered at Mawson. Equipment and facilities for glaciological went were limited, but a wide range of topics was studied. The results obtained in the field were analysed in Melbourne in conjunction with the Meteorology Department, Melbourne University, during the austral winter of 1958, and in the summer of 1959 the author was given the opportunity of returning to Antarctica in the m.v. "Magga Dan" to make further studies and to install at Wilkes base equipment developed from experience gained in 1957. Some results have already been published, but in the present thesis the observations which lead to an outline of the mass economy of the ice cap have been brought together. After giving a general account of the nature and behaviour of the ice cap the accumulation of snow on the surface of the ice is described and the transformation of snow into ice is touched upon. Measurements of accumulation from MacRobertson Land are compared with similar ones from other parts of Antarctica and values leading to an accumulation estimate for the whole ice sheet are introduced. The agencies responsible for removal of ice from the continent are then discussed and measurements of ice flow, ablation, and wind-blown snow are given, together with descriptions of the measuring techniques used. A still undetermined factor in the Antarctic mass budget, oceanic melting beneath ice shelves, is briefly discussed. Since the mass budget, towards which the observations lead, is intended to show whether or not the ice cap is in equilibrium at present, direct observations on fluctuations of ice level are given in the chapter dealing with past and contemporary variations in the positions of the ice margins. Finally, mass budgets for the region studied and for the whole of Antarctica are drawn up. The average precipitation over Antarctica is estimated and the ice import and export estimates are compared, showing a large surplus of accumulation over ice loss. This apparent indication of a growing ice cap is regarded with some doubt and it is concluded that more data are needed before this result can be accepted.
Studies on the effects of chelating agents and other compounds on plant growth

Kok, Ng Eng. (University of Melbourne, 1958)
Studies on translocation in plants

Thaine, Robert. (University of Melbourne, 1957)

Science Collected Works - Theses

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