Australian Academy of Science Biographical Memoirs of Deceased Fellows Originally prepared for publication as part of Bright Sparcs by the Australian Science Archives Project.

Alexander John Nicholson 1895-1969

Alexander John Nicholson was born at Biackall, Co. Meath, Ireland, on March 25th, 1895. His parents had also been born in Ireland, although both came from English yeoman families of, at least on his mother's side, powerfully Methodist convictions. His father was a successful designing engineer, his mother a woman of acute and independent mind, and his elder brother an inventive member of the Royal Flying Corps. Of his two younger sisters, Nan, a trained kindergarten teacher, lived in Canberra for some years during the thirties and established the first preschool centre on the northern side of the young city.

The Nicholsons moved to England, where John (he appears never to have been known as Alexander) spent the rest of his childhood, except for holidays in Ireland. He shared the family bent for mechanisms and gadgets and the exciting new motor cycles, cars and aeroplanes, but his special interests were in photography and natural history. He became a member of the Birmingham Field Naturalists' Club (annual subscription one shilling) when twelve years old and, to balance it, joined the Midland Aero Club at fifteen, although there is no record that he actually flew. He entered the Waverley Road Secondary School, then remarkable for its new science laboratories, in 1908, and, despite some concern by his masters that he was more interested in natural history than in his formal subjects, matriculated with honours and an entry prize into Birmingham University in 1912. He graduated B.Sc. in 1915 with First Class Honours in Zoology, Chemistry as a second subject, and Botany as a minor. He was not impressed with the course in chemistry, which consisted almost entirely in covering the board with structural formulae of dyestuffs, nor with what he termed the 'necrological approach' to zoology, which was concentrated on comparative anatomy and ignored physiology and the activities of living animals. Still he did get a grounding in classical evolutionary theory.

Then came the 1914-18 war. Already a member of the University OTC, Nicholson was commissioned 2nd Lieutenant in the Royal Field Artillery in 1915. He spent most of the next two years instructing - strenuous, because they were only allowed six weeks in which to produce gunners - and the rest of the war on active service in France and Belgium. He was promoted to 1st Lieutenant, twice mentioned in despatches,and awarded the King's Commendation for bravery. The war left him with a cardiac lesion that limited strenuous activity for the rest of his life, and it was characteristic that even his closest friends did not know of this until after his death.

He returned to Birmingham in 1919 to begin postgraduate research on two entomological problems: ecology of the natural enemies of Chermes, an homopteran pest of pine trees; and development of the ovaries in the mosquito Anopheles maculipennis. The latter was a particularly neat piece of work, which has been referred to as a source of information even in recent publications, and he received an M Sc. for it in 1920. In March 1921 he was appointed the first McCaughey Lecturer in Entomology in the University of Sydney and given permission to spend some months studying entomological research and teaching in U.S.A. on his way to Australia. He was profoundly impressed by all that he saw, and especially by the high quality of applied entomology in that country. That trip was a sound investment by the Senate of the University.

When Nicholson arrived in Sydney in October 1921, he was a slim, fresh-faced, rather shy young Englishman. He seemed at first to be rather hesistant, but nothing was further from the truth: he knew exactly what he wanted and (although he would never have thought to say so) intended to get it. He began with one great local advantage. The nominally independent McCaughey lectureship was associated with the Department of Zoology, which had recently been taken over by Launcelot Harrison who was rapidly transforming it into what was, during his too brief tenure of the Chair (he died in 1928), probably the keenest and most friendly department in the Faculty. Harrison welcomed Nicholson to his academic family. It was not difficult, because they were both first-class naturalists, they had both served in the British Army (the one in Palestine, the other in Europe), they were equally determined not to rear their students on an undiluted diet of morphology, and, although temperamentally poles apart, they were both fundamentally friendly people. In any case, no one could remain shy or inarticulate for long in the atmosphere that Harrison was fostering, and Nicholson was very responsive to goodwill.

Up to 1921, entomology was taught as a fragment of the Arthropoda in Zoology, and (by W.W. Froggatt) as a mixture of rather primitve natural history and blunderbus control measures in Agriculture. It was Nicholson's job to give it substance in both faculties, and this was urgent, because, as his observations in America had shown him, training by apprenticeship was just not good enough any longer in either the academic or-the economic field.

It is useful to pause at this point to consider the state of entomology in Australia, particularly in Sydney, fifty years ago. The professionals were all self-trained or had served some form of apprenticeship. Thus, W.W. Froggatt, Government Entomologist in New South Wales from 1896 to 1923 and a most prolific writer, got most of his training as a collector for Sir William Macleay; his successor, W.B.Gurney, joined the department in 1900, but did not obtain a B.Sc. (presumably as a part-time student) until 1925. In fact, A.R. Woodhill (who had the best of both worlds by taking Froggatt's course in 1920 and Nicholson's in 1923, and who succeeded Nicholson in the University in 1930) was, when he joined Gurney in 1924, probably the first graduate entomologist to be appointed to a Department of Agriculture in Australia. The situation was similar in the Museums, and in the Commonwealth there were only F.H. Taylor and G.F. Hill who, up to that time, had been mostly concerned with medical entomology. Almost all these people who were paid for being entomologists had built their careers on a very modest level of secondary education.

The insects attracted few students in the universities. In Brisbane T. Harvey Johnston had two young graduates, Josephine Bancroft and O.W. Tiegs, who later became eminent, and in Sydney Harrison had done notable work on Mallophaga (most of it, actually, while he wasin Cambridge). By far the most distinguished was R.J. Tillyard, a Cambridge graduate, who must rank in part with the amateurs, for he was a school teacher for several years before resuming academic life in Sydney University in 1913 as a Research Scholar and subsequently a Linnean Macleay Fellow. He went to the Cawthron Institute in New Zealand in 1920, was elected to the Royal Society of London in 1925, produced his classical Insects of Australia and New Zealand in 1926, and returned finally to Australia in 1928.

In fact, productive work in entomology at that time was predominantly taxonomic and predominantly in the hands of educated amateurs, mostly professional men with rather more leisure than is common today. Some of the most productive, in terms of publication, were A.J. Turner (Lepidoptera) and A.E. Shaw (Blattodea) in Brisbane; G.A. Waterhouse (Lepidoptera), H.J. Carter (Coleoptera), E.W. Ferguson (Diptera and Coleoptera), and R.J. Tillyard from 1907 to 1913 (Odonata) in Sydney; and the Rev. Thomas Blackburn (Coleoptera) in Adelaide. Of these seven, three were medical practitioners, one a metallurgical engineer, two schoolmasters, and one a clergyman. All were active in the local scientific societies, the Sydney group particularly in the Linnean Society of N.S.W. and a small but lively entomological section of the Royal Zoological Society of N.S.W.

To return to the University, Nicholson was given a detached laboratory at the western end of the Zoology School, sufficient McCaughey funds to equip it modestly, the services of Miss Gwen Burns, a very competent photographic assistant in the Zoology School, and the task of preparing two sets of classes. The more urgent, first given in 1922, was a short introductory course in first year and a full one in second year in Agriculture; the other a two-term course that could be taken by Science students as an alternative to vertebrate zoology. Nicholson described his plan, in retrospect, in the following words:

The basis of both courses was general systematics, morphology, and general biology. Only sufficient of this was given to Agriculture students to provide a firm basis for an intelligent development of the subject of economic entomology, to which I naturally had to devote as much time as I could. With Science students I made little more than passing reference to insect pests and their control, treating entomology simply as a component of Zoology and going into greater detail with morphology, systematics and biology.

He had to face three problems in putting his plans into effect. He had to obtain a knowledge of the strange Australian fauna that he was seeing for the first time, to devise means to bring his courses to life, and to learn about the pest species and their control. The last was the easiest. Many of the pests were immigrants (or at least related to northern-hemisphere species), he already knew something of the situation in Europe and America, and he was able to obtain State departmental help, particularly from Gurney, to fill in the local picture. The need was to foster a new approach, rather than to look for new pests.

The only solution to the first problem was to go into the field and learn for himself. His first trips were to Woy Woy and the Blue Mts with Tillyard and A.L. Tonnoir, who were visiting Australia to fill gaps in their own research material, and Harrison took him to the Blue Mts and Mt Kosciusko; but he received the greatest help from the band of able, enthusiastic amateurs mentioned earlier. He was quickly elected to the Linnean and Royal Zoological Societies and joined in their discussions (especially over coffee after the meetings), but, more important, somebody was always going off in the week ends, or even during the week, to collect in some favourite spot. G.M. Goldfinch, a lepidopterist, had a roomy Essex car which he regularly filled with congenial entomologists, Waterhouse and Ferguson had cars too, Nicholson later acquired a Morris Cowley of his own, and there were frequent parties to the Zoological Society's cottage in the National Park (especially in the early spring), to many other parts of the Hawkesbury Sandstone area at all seasons, and sometimes further afield. A notable later trip that he made was with P.D.F. Murray to Papua and New Guinea. On these trips Nicholson always seemed to be dawdling behind the rest of the party, but he regularly ended up with a greater no. and variety of specimens than any one else. There was, too, considerable mutual stimulation, the specialists widening their interests to all orders under his influence and he learning a great deal about their own groups from them. That was not always true, for sometimes he could show them something they had not known about the biology of their own species.

The results of these activities were a remarkably wide knowledge of Australian insects (second only to Tillyard's) acquired in a remarkably short time, and a notable teaching collection of which Mrs. J.W. Evans (a daughter of Tillyard and herself an entomologist) wrote much later:

. . . it became my responsibility for a year or two to care for the [Zoology] Department's entomological collections. A great deal of this had been collected by Nic across his Sydney years and I was amazed at the industry and the vastness of the field he had covered. It goes without saying that it was all, over 30 years afterwards, perfectly mounted and preserved and it brought alive most vividlyA.J.N.'s early field trips in Australia.

There remained the problem of balancing his teaching with an adequate leavening of general biology. The special physiology of insects was little known at that time, but Nicholson taught what he could, sometimes, he thought, rather rashly. He inaugurated field excursions to show his students how insects lived and what they did, but there was not room in the timetable for enough of them. As well as pinned adults, his collections included immature stages and the results of insect activity, and these could be used in practical classes; but that was still not enough, so he resolved to supplement his efforts by photography. This could be done in the laboratory, where he was ably assisted by Miss Burns, or in the field, for which he developed an ingenious telescopic range-finder for his camera and learned to use flashlight effectively both in shade and at night. He photographed everything of interest that he saw, and thus was able to illustrate his lectures by a remarkable series of lantern-slides of larval and adult insects going about their normal business in their natural habitats. Nearly forty years later he adapted a Leica camera to do the same work in colour.

The history of entomology in Australia has been divided(1) into four periods: Fabrician (1770-1860) when explorers sent their material to Europe for study; Macleayan (1861-1890) when the study came increasingly to be done in Australia; the period of the amateurs touched on earlier; and the period of the professionals. Nicholson's arrival marked the beginning of the transition between the last two. He put university teaching on a firm scientific foundation, and provided the first agricultural graduates to bring a new approach to economic entomology in this country. He had few students in pure science (Mary Fuller, who died young, was the most promising), and it was not until a separate honours year was instituted by the Faculty of Science after he left that the foundation he laid could be built on effectively. Nevertheless, the wind of change was blowing steadily and with increasing strength. Lectureships (and one Chair) were established in other universities, the demands of State departments grew steadily, and the Commonwealth established the Council for Scientific and Industrial Research (CSIR) in 1926 with G.A. Julius, A.C.D. Rivett and W.J. Newbigin (succeeded in 1927 by A.E.V. Richardson) as its first Executive. Young people interested in insects nolonger became doctors or schoolteachers and devoted their leisure to their hobby; they took an appropriate degree in a university and made entomology their profession, with ever widening fields of research and ever increasing technical and financial resources before them. It could fairly be said that, so far as Australia is concerned, Nicholson in a sense began it all.

In 1927 he found himself with the task of preparing a presidential address for the Royal Zoological Society of N.S.W. He looked through his slides to find what subject he could illustrate best, and decided on mimicry. At about the same time a bright student had raised doubts about the generality of the rather crude concepts of population dynamics that then prevailed. This concurrence of unrelated events led to the production of a very important paper which has not received the attention it deserved. He not only gave a comprehensive review of mimicry and concealing coloration in Australian insects and demonstrated the reality of the phenomena, he also stated the basic principles and hypotheses that he was to spend much of the rest of his life in testing and amplifying. In brief, the thesis he developed was that animal populations could not survive in nature unless their densities were governed by some regulatory (feed-back) mechanism that was density-dependent in its operation; that success in searching for essential resources was the only mechanism that was truly density-dependent, all others being merely modifying; that the 'power of discovery' of natural enemies could regulate the abundance of both parasites and hosts; and that natural selection did not determine survival and abundance, it merely ensured that any form of a species that acquired an inheritable advantage, however slight, would progressively replace the previously successful form. In the immediate context, survival and abundance of the mimetic or procryptic insects studied seemed clearly to depend on density-dependent stresses operating on their immature stages, the perfection of their concealment or mimicry on quite minor selective pressures imposed by predators on the adults. The theory was well documented, it gave a credible explanation of the phenomena observed, and it was free from the objections that had been raised against previous theories, some of which, as Nicholson pointed out, were due to failure to understand what Darwin had meant by natural selection. For this work he was awarded a D.Sc. of Sydney University in 1929.

He then concentrated on theoretical population dynamics, using arithmetical models of situations approximating to ones that he knew occurred in nature, and examining more particularly, though not exclusively, various kinds of host-parasite interactions. He soon found, to his surprise, that the equilibrium produced was not a steady one, but generally more or less violently fluctuating. V.A. Bailey came into collaboration with him at this time, using more sophisticated mathematical treatment that gave generality to the results, and they found that the fluctuations were due to time displacements associated with length of life cycle. They wrote a book (finished in 1931) on the theory and its implications, but it was 'too theoretical' to find favour with the publishers' readers of the day, and their results ultimately appeared in a rather scattered series of joint and separate papers.

In the mean time, R.J. Tillyard had returned to Australia in 1928 as Chief of the newly established Division of Economic Entomology of CSIR. He gathered the nucleus of a staff about him, and they set about helping him to plan the research and the laboratories at Canberra. Tillyard proved to be an extraordinarily stimulating scientist, but an unpredictable administrator. To balance this, the Executive appointed G .A. Waterhouse (then Curator of the Division) as its Executive Officer. He remained only a year, and in 1929 Nicholson was offered the position of Deputy Chief. He accepted on the condition that he should spend most of 1930 in England as he had already planned. He undertook a no. of enquiries for the Division while abroad, and arrived in Canberra towards the end of that year.

He found his position difficult, and the times were difficult too; no new developments could be planned, so he sought transfer, as a Senior Entomologist, to the sheep blowfly investigations, which had been established before the depression began. During the next year and a half, he helped to guide the entomological side of the Section's work and began two pieces of personal research. One was a study of traps and baits, for which he designed ingenious ways to reduce the action of external variables, and the other a study of the effects of temperature on the activity of the adult flies. Tillyard became ill before the trapping studies were completed(2), Nicholson was appointed Acting Chief in April 1933, and from then on he had little opportunity for personal research until after the war.

In 1933 he married Phyllis Heather Jarrett, M.Sc., a former CSIR research student and at the time a plant pathologist in the Division of Plant Industry, and she assisted him for some years thereafter as an unofficial technical secretary. They had two sons, Garth Alexander, who was a CSIRO scholar at Geelong Grammar School and graduated M.B., B.S. (Sydney) in 1967, and Peter John, who graduated B.Ec. (Sydney) in I968.

The financial situation was still precarious in 1933, and the Executive had not been happy about some of the Division's work. Nicholson, aided by his senior staff (G.F. Hill, I.M. Mackerras, G.A. Currie, A.L. Tonnoir), gave it stability during this period. He-planned with great care, and strove especially, as he did in all subsequent years, for a judicious balance between fundamental and applied research. He emphasized, indeed, that the need for fundamental research was probably greater at that time in economic entomology than in any other applied science. The Executive were irritated by the, to them, inordinate time he often took to develop his proposals, but they came to respect the final clarity of their presentation, their wisdom, and his unswerving scientific integrity. His appointment was confirmed in 1936. The same qualities - and Rivett's support - held the Division together during the following years, when there were moves to abandon taxonomy to the museums and distribute some of its other activities among the sister Divisions to which they were relevant.

Tillyard's main theme had been biological control of weed and insect pests. Some of his people had already found it necessary to approach their problems more broadly, and Nicholson further widened the approach and the range of problems under study. Biological control remained an important activity, but on a more cautious and critical basis; ecology, with emphasis on the interactions of the animals rather than the physical background, became the major theme in most investigations; biochemical studies increased; physiology and toxicology found a specific place in 1938; important protozoological and virological investigations were undertaken for the Division of Animal Health; and taxonomic research expanded. It was a fertile period, too, in the studies of life histories and general biology of the insects. In 1938 he visited research institutions abroad, and gave a paper to the 7th International Congress of Entomology in Berlin, in which he stressed the fundamental importance of detailed ecological studies of pest populations in planning the use of pesticides and assessing the results achieved. This paper was the forerunner of the modern concept of strategic pest control.

The war affected the Division in two ways: it took away nearly a third of the scientific staff on active service, and it caused a reorientation of the efforts of those that remained. In particular, a strong team, initially under F.N. Ratcliffe, was directed to studies of the pests of stored products, with results of substantial value to the general war effort; and D.F. Waterhouse did very valuable work in collaboration with the army medical services on the development of repellents and other entomological aspects of the control of malaria and scrub typhus. Ratcliffe became an Army malariologist; Waterhouse was appointed to the Reserve of Officers to be called up as needed, and so close was the collaboration that it was difficult to know at any given moment whether he was on active service or a civilian scientist. Nicholson strongly supported all these activities, served on the Medical Services Advisory Committee, and, in his spare time designed an acoustically controlled torpedo for use against submarines.

The atmosphere became more favourable after the war. The Division had rnade its mark, there were increasing demands for a greater range and diversity of studies, and the Executive had come to appreciate the importance of Nicholson's own field, and his reputation in it, more fully than they did before the war. Cattle tick research (begun during the war) became a major activity; the work on pests of stored grain was continued, ecological studies were extended to pasture, forest and fruit pests not previously investigated; much was to be learned about the new insecticides that had been developed during and after the war; the concept of integrated control was beginning to take shape; a distinguished school of insect physiology and biochemistry was growing up in the Division; studies of the transmission of plant viruses were begun; and a small unit of experimental population dynamics was set up for Nicholson's own work. The rate of staffing shows the overall growth most simply. In 1929, when the Canberra laboratory was occupied, the scientific staff (including graduate assistant and equivalent) was 12; in 1933, when Nicholson took over from Tillyard, it was 16, rising to 23 in 1939, and falling (in effect) to 14 during the war. It rose again to 29 in 1946, 37 in 1949 and 43 in 1959(3). All this expansion threw additional burdens on the Chief, and he was given progressively increasing administrative assistance to cope with them. This enabled him to do some personal research, though never as much as he could have wished.

Nicholson disliked rigid sectionalization of research and an hierarchical arrangement of staff. His policy was 'to give each research worker full responsibility and great freedom within his allotted field of investigation', and to draw all members of a team into the planning of that team's activities. To these ends, he gradually abolished most of the pre-war sections, replacing them by three broad groups - taxonomic, ecological, physiological-biochemical - and substituting leadership resulting from recognized ability for direction. Of the three groups, taxonomy and physiology-biochemistry were relatively clearly defined, ecology more loosely linked and occupied with a less coherent range of problems and activities. There was, however, considerable flexibility. Thus, veterinary entomology and termite research retained much of their sectional identity, but with links in all three directions, and some more isolated investigations, such as the earth mite and lucerne flea studies in Western Australia, remained relatively discrete. He stressed, too, that physiological and biochemical problems could usually be defined with comparative precision and lead to the production of neat, scientifically acceptable papers, though also revealing very quickly the deficiencies of an inadequate worker; whereas ecological work generally lacked an established theoretical foundation, and was consequently likely to be relatively diffuse and productive of long, less immediately satisfying publications. The assessment of merit in these divergent fields worried him. Nevertheless, he had a keen eye for work that was intellectually demanding and likely to be intellectually rewarding, and his policy seemed, in general, to work very well. The Division was successful, which is the crucial test.

Nicholson completed his term as Chief in March 1960, and was appointed to a Senior Research Fellowship to continue his twin studies of population dynamics and natural selection. His unit was also retained for long enough to finish the experiments he had already planned, but his main task was to prepare his findings for publication. This had not been completed when he became ill, his damaged heart failed, and he died on October 28th, 1969.

It is difficult to give a brief account of his population studies because they are inherently complex and have been bedevilled by criticism and misunderstanding. It is, in fact, necessary at the outset to repeat his basic postulate in purely general terms, as all his major conclusions follow from it and it has been completely ignored by all his major critics. It is simply that no intrinsically variable phenomenon can continue to exist in the absence of a feed-back mechanism to limit its variability; in the specific context, animal populations, in places where they can exist at all, are governed fundamentally by processes that are density dependent, all other influences being merely modifying, and the actual population level at any moment being the result of interaction between the governing and modifying processes. It is to be noted, too, that the differences between the two sets of processes are qualitative, not quantitative, a fundamental point that critics have also failed to appreciate.

In the first, rather extended phase, as already noted, he developed a complex structure of theory by applying his basic premise to a variety of imagined natural situations. After the war, he was able to test many of his conclusions on experimentally manipulated populations. Initially, following I.S. Srnith and his colleagues of Riverside, California, who had arrived independently at essentially similar conclusions, he used housefly puparia and the parasite Nasonia vitripennis. These gave trouble, so he turned to the sheep blowfly, Lucilia cuprina, which had proved itself to be a remarkably biddable laboratory animal, and he abandoned the examination of host-parasite interactions (temporarily, he thought) for a detailed study of intraspecific competition. Most of the results of this phase were presented, at least in outline, to various congresses and symposia, of which he attended no less than six between 1947 and 1959. It is worth noting, in view of criticisms that have been made of laboratory ecology, that the field ecology of L. cuprina had been studied in considerable detail by Mary Fuller(4), and that Nicholson's findings, though quantitatively much more precise, were completely in accord with hers.

In his mimicry paper he had developed the theme of random search and discovery as the basis of density-dependent reactions, but he soon transferred the emphasis to the competitive element that is inherent in the search, and he used the word 'competition' in this sense (sometimes to the confusion of his critics) in all his subsequent work. Basically, in his view, populations of any species are governed (not determined) by some form of intraspecific competition for essential resources (nutrients, places to live, and so on)(5), but this can produce two distinct results. Usually (as with flies in carrion) provision of the resources is independent of the population, so their varying level in the environment serves simply as a modifying influence: only the single population is governed. When, however, the resource is itself a living organism and the association is sufficiently specific and destructive, the populations of both predator and prey (or parasite and host) are governed by the competition among the attackers for their essential living resource, each population interacting with the other. This is what has happened, for exarnple, with Cactoblastis and prickly pear. On the other hand, in more usual forms of interspecific competition (as between different species of blowflies in a carcass) each species acts merely as a modifying influence on the others' populations.

Balance is the resultant of two opposing 'forces', the reproductive capacity ('power of increase') of the organisms on the one side, and the governing + modifying stresses on the other, the level of balance varying with changes in any of the three components. Thus the 'steady density' is always more or less unsteady in natural populations. Reproductive capacity is always greater, generally very much greater, than is necessary to maintain populations under favourable conditions, and Nicholson stressed that this gives the population great resilience in coping with adversity, as was abundantly demonstrated in his experiments. For example, in a stabilized population governed by competition for larval food, destruction of 99 per cent. of the adults before they could lay eggs resulted (through relaxation of the larval competition) in a compensatory six-fold increase in the no. of pupae maturing in the next generation. This effect could be maintained indefinitely by continuing the destruction of adults in succeeding generations, and it could be produced equally well by replacing mechanical destruction by competition between the adults for limited supplies of the protein food necessary for them to mature their eggs. That last series of experiments was particularly interesting, because it was found that larval competition could be replaced completely by adult competition; and, when mutant adults capable of maturing eggs on progressively smaller quantities of protein appeared and became selected in these cultures, balance was still maintained, but at progressively altered levels; until, finally, mutants able to mature eggs without any protein food also appeared and the population showed evident indications of beginning to explode.

These are the broadest of Nicholson's conclusions (with some illustrative examples) and they should be applicable to all animal populations - and presumably to plant populations too. However, his models were insects, in most of which there is a sharp ecological dissociation between the larval and adult populations of the species, and some of his subsidiary findings may depend upon that fact. The phenomenon of oscillation, which he examined in great detail in his later work, may be one, and so too may be some of the detailed results mentioned above. On the whole, however, it would appear that the disadvantages of using models with specialized life cycles were more than offset by the advantages of being able to define and measure their population structure with accuracy and precision.

Other aspects of intraspecific (and some of interspecific) competition could have been quoted, and the interactions between natural enemies and their hosts were studied in similar detail, though only at the theoretical level. In short, by his meticulous examination of the ways in which both governing and modifying processes could act, and of the manifold effects of altering them, Nicholson provided a system of thought which could serve as a basis for modern work on integrated control and pest management. This, indeed, was an aim that he himself had clearly in mind.

He was a slow worker (each experiment had in any case to run for at least eight months and often much longer) and an even slower writer. He was greatly concerned with the use of words and spent a great deal of time in choosing exactly the right ones to convey his meaning-and perhaps even more in eliminating redundancies and compressing what he had to say into the minimum amount of space. This made for clarity, but not always for easy reading. He was, too, sensitive to criticism, and inclined to spend more time than it warranted in answering it. The famous controversy with Andrewartha and Birch is a case in point. However, the crux of the problem lay in the complexity of his subject. Knowing, as a realist, that the time before him must steadily be growing shorter, he endeavoured to break his material into a series of papers to be completed sequentially, but at every turn he found himself faced with points that required cross-reference to other parts still not written. This grew so distracting that he reverted to his original plan to put it all into a single book. He was still organizing this when he died. He left notes, graphs, and experimental records in very good order, and it is to be hoped that some one expert in the field may be found to integrate them into something resembling thetreatise that he did not finish.

His studies of natural selection were more complete, though not all of his experimental evidence got into his published reports. What he did, in essense, was to clarify what Darwin and Wallace meant by natural selection and show how it worked. His thesis may be summarized in five statements.

1. Fitness, in the sense of Darwin and Wallace, is relative, like the fitness of the tall player who can manipulate a basket-ball over the heads of his shorter fellows.
2. There are two kinds of natural selection: environmental (Wallacean) in which the less fit are eliminated in periods of adversity; and competitive (Darwinian) in which the more fit displace the less fit in the struggle for existence, whether the environment varies or not. Both operate, alone or in conjunction, the Darwinian being the more powerful and the only one that can, by itself, lead to improved exploitation of the environment.
3. Natural selection operates in balanced populations which have inherent resilience in coping with variations in environmental stresses - that is, a substantial degree of homoeostasis. Consequently, any variant that possesses an inheritable quality giving it an immediate advantage, however slight, will progressively displace the previously successful members of the population, and the governing mechanisms will progressively adjust the balance to meet the new circumstances. Selection, in fact, is limited only by the capacity of the gene pool to produce advantageous variants, and hyperadaptation is the normal end result. All these occurrences were observed in the experimental populations of Lucilia cuprina, of which an example has been given above.
4. There is nothing purposive in natural selection. Population levels are not determined, nor necessarily much influenced, by it, nor has it necessarily anything to do with survival of the species. It can produce novelties, which may be ultimately disadvantageous like the antlers of the Irish elk, or potentially advantageous like his own strain of flies that could mature eggs without a protein meal; it does ensure 'biological improvement' of the population; and it can assist indirectly (as well as directly) in the process of speciation.
5. The post-Darwinian concept of selection producing a precise fit between organism and environment, like the exact fit of a complicated key in its lock (Fisher), is false. There is no need for this kind of 'fitness', no evidence that it exists, and no way in which either Darwinian or Wallacean natural selection can produce it. Inferences that have been based on it should therefore be re examined.

Looking at his publications as a whole, three stand out as having all the qualities of enduring classics: the 1927 study of mimicry, which has been too badly neglected; the 1933 statement of population theory, of which C.A. Fleschner, of Riverside, wrote (in litt.) in 1970 that it was far superior for teaching the principles of biological control to anything that has been published since; and the 1960 analysis of natural selection, which is so well documented that it should have a deep influence on modern thinking in population genetics and evolutionary theory.

Like his father and brother, Nicholson was an inventive designer of equipment. He delighted in gadgets, as he did in words and their uses, but always for the functions they could perform in solving problems that concerned him. His own were aesthetically pleasing, because they did exactly what was required of them with a minimum of complication and effort. A few have been mentioned on earlier pages, the remainder were developed for his population studies. They included simple tissue grinders (published in 1951) that distintegrated all cells and most nuclei, photoelectric equipment to count blowfly eggs, a fractionater for separating the stages of Lucilia cuprina, a pneumatic method of capturing living flies, and an instantaneous vacuum cleaner for collecting empty puparial shells. Descriptions of the last two were left in a sufficiently advanced state to be completed as a posthumous publication.

He had another great interest, but lightly touched on so far, and that was his love of natural history. Wherever he went, he observed, photographed, and collected. After the war, he and his wife acquired a week-end cottage at Bawley Point on the coast, where they spent most of their leisure, and where he brought his colour photography to its highest level. He did not confine himself to insects, but photographed birds, frogs, plants, and indeed any living thing that caught his eye; he even developed underwater equipment to record the doings of marine animals, and used it to great effect when he visited a coral cay. He extended his records of mimicry, made new observations on pollination of orchids by male wasps, and studied the stridulatory mechanism of the whistling moth. His opportunities increased after he retired as Chief, and still more when his research fellowship ended officially in 1966, although he continued to work in the laboratory . The last nine years, when he was free from responsibility and could do what he thought most satisfying, were probably the happiest in his life.

His love of natural history was reflected also in his strong support of conservation in ANZAAS and Academy deliberations, and in the very active part he played in the successful effort of the Royal Society of Canberra to get the Tidbinbilla Fauna Reserve established.

Nicholson had his share, too, in the gregarious activities of scientific societies. He was elected to the Linnean Society of N.S.W. in 1922, served on Council in 1928-29, and remained a member until his death. He was a member of the Royal Zoological Society of N.S.W (President 1926-27) and of the Royal Society of Australia(6) (President 1951, Council for several years); foundation member of the Australian Institute of Agricultural Science, the Ecological Society of Australia, and the Australian Entomological Society; foundation President of the National Parks Association of A.C.T.; and a Fellow of ANZAAS (President of Section D 1947). He was a Foundation Fellow of the Academy, its first Biological Secretary in 1954-55, Vice-President in 1955-57, the first 'amicus curiae' appointed to serve as a link between the young Council and the even younger Sectional Committees, and the initiator of the Academy's proposal to the Commonwealth government for establishment of a research museum of Australian biology in Canberra. He made a significant contribution to the stability and steady growth of the Academy in those early difficult years.

He received several awards in addition to his higher degrees: the Clarke Medal of the Royal Society of N.S.W. in 1952; C.B.E. in 1961; Honorary Fellowship of the Royal Entomological Society of London in 1961; and Honorary Membership of the British Ecological Society in 1963, the only worker in Australia to have been so honoured. He will be long remembered for initiating the professional era in Australian entomology, for his contributions to the development of the Division of Entomology in CSIRO, for the publication of three enduring classics, and, by those who knew him, for his quiet friendliness, wise counsel, and complete integrity.

This account of John Nicholson's life and times was based on his own notes, on information provided mainly by Mrs. Phyllis Nicholson and Dr. D.F. Waterhouse, and on the memories of my friendship that lasted for forty-eight years.

Notes

(1) Proceedings of the Royal Society of Queensland, 60 (1949). pp. 69-71.

(2) In any case, concurrent studies in the field were beginning to throw considerable doubt on the potential value of trapping as a control measure.

(3) CSIR became CSIRO and the Division dropped 'Economic' from its title in 1949. Its scientific staff has since grown to 95 in 1969.

(4) CSIR Bulletin no.  82 (1934)

(5) He distinguished between two kinds of competition: 'scramble', a continuing struggle which is wasteful of resources and leads to violent oscillations in population density; and 'contest', as in territorial animals, which conserves resources and results in steadier population levels.

(6) Royal Society of Canberra from 1955.

Ian Murray Mackerras, F.R.A.C.P., is a Research Fellow in the Division of Entomology, CSIRO. He was elected a Fellow of the Academy in 1954 and was on the Council in 1955-57.

This memoir was originally published in Records of the Australian Academy of Science, vol. 2, no. 1, Canberra, Australia, 1970.