Table Of ContentPERSPECTIVES
IN
EXPERIMENTAL BIOLOGY
Volume 2 Botany
Proceedings of the Fiftieth Anniversary
Meeting of the Society for Experimental
Biology
Edited by N. SUNDERLAND
With the editorial assistance of
E. W. SIMON, J. HESLOP-HARRISON, P. W. BRIAN and D. A. BOULTER
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LIST OF CONTRIBUTORS
ATTRIDGE, T. H., Department of Physiology and Environmental Studies, University of
Nottingham School of Agriculture, Sutton Bonington, Loughborough, Leics., U.K.
BALDRY, C. W., Tate & Lyle Limited, Group Research and Development, P.O. Box
68, Reading, U.K.
BATT, T., Department of Plant Sciences, Baines Wing, University of Leeds, Leeds, U.K.
BOWLING, D. J. F., Department of Botany, University of Aberdeen, U.K.
BRADBEER, J. W., Department of Plant Sciences, University of London, King's College,
68 Half Moon Lane, London, U.K.
BRUINSMA, J., Department of Plant Physiology, Agricultural University, Wageningen,
The Netherlands.
BUCKE, C, Tate & Lyle Limited, Group Research and Development, P.O. Box 68,
Reading, U.K.
BUTT, V. S., Botany School, South Parks Road, University of Oxford, Oxford, U.K.
CALLOW, MAUREEN E., Department of Plant Sciences, University of Leeds, Leeds, U.K.
CLARKSON, D. T., A.R.C. Letcombe Laboratory, Wantage, U.K.
CLOWES, F. A. L., Botany School, South Parks Road, University of Oxford, U.K.
COOMBS, J., Tate and Lyle Limited, Group Research and Development, P.O. Box 68,
Reading, Berks, U.K.
DAVIES, D. D., School of Biological Sciences, University of East Anglia, Norwich, U.K.
DOUGHERTY, C. T., Department of Plant Science, Lincoln College, Canterbury, New
Zealand.
ELLIS, R. J., Department of Biological Sciences, University of Warwick, Coventry, U.K.
EVANS, L. V., Department of Plant Sciences, University of Leeds, Leeds, U.K.
FOWDEN, L., Rothamsted Experimental Station, Harpenden, Herts, U.K.
GILCHRIST, A. J., Botany School, South Parks Road, University of Oxford, Oxford, U.K.
GORE, J. R., Department of Botany, University of Edinburgh, Mayfield Road, Edinburgh,
U.K.
GOULD, A. R., Botanical Laboratories, School of Biological Sciences, University of
Leicester, Leicester, U.K.
ix
χ LIST OF CONTRIBUTORS
HEATH, Ο. V. S., 10 St. Peter's Grove, London, U.K.
HESLOP-HARRISON, YOLANDE, Cell Physiology Laboratory, Royal Botanic Gardens,
Kew, London, U.K.
HUMPHREY, T. J., School of Biological Sciences, University of East Anglia, Norwich,
U.K.
INGLE, J., Department of Botany, University of Edinburgh, Mayfield Road, Edinburgh,
U.K.
JACKSON, S. MARGARET, Department of Biology, University of York, Heslington, York,
U.K.
JOHNSON, C. B., Department of Physiology and Environmental Studies, University of
Nottingham School of Agriculture, Sutton Bonington, Loughborough, Leics., U.K.
JUNIPER, Β. E., Botany School, South Parks Road, University of Oxford, Oxford, U.K.
KING, JOHN, Botanical Laboratories, School of Biological Sciences, University of
Leicester, Leicester, U.K.
LANGER, R. H. M., Department of Plant Science, Lincoln College, Canterbury, New
Zealand.
LEAVER, C. J., Department of Botany, University of Edinburgh, Mayfield Road,
Edinburgh, U.K.
LEECH, RACHEL M., Department of Biology, University of York, Heslington, York,
U.K.
LEFTLEY, J. W., Department of Botany and Microbiology, University College, Swansea,
U.K.
LEWIS, D. H., Department of Botany, University of Sheffield, Sheffield, U.K.
LILLEY, R. McC, Department of Botany, University of Sheffield, Sheffield, U.K.
LOUGHMAN, B. C, Department of Agricultural Science, Parks Road, University of
Oxford, U.K.
LOVETT, J. S., Department of Biological Sciences, Purdue University, West Lafayette,
Indiana, U.S.A.
MACROBBIE, ENID A. C, Botany School, University of Cambridge, U.K.
MANSFIELD, Τ. Α., Department of Biological Sciences, University of Lancaster, Bailrigg,
Lancaster, U.K.
MEIDNER, H., Biology Department, University of Stirling, U.K.
MILBORROW, Β. V., Shell Research Limited, Milstead Laboratory of Chemical Enzy-
mology, Sittingbourne Research Centre, Sittingbourne, Kent, U.K.
MILTHORPE, F. L., Macquarie University, N. Ryde, 2113, Australia.
LIST OF CONTRIBUTORS xi
OSBORNE, DAPHNE J., Agricultural Research Council Unit of Development Botany,
181A Huntingdon Road, Cambridge, U.K.
RAVEN, J. Α., Department of Biological Sciences, University of Dundee, U.K.
ROBARDS, A. W., Department of Biology, University of York, Heslington, York, U.K.
RUSSELL, R. SCOTT, A.R.C. Letcombe Laboratory, Wantage, U.K.
SCHWABE, W. W., Wye College, University of London, Wye, Kent, U.K.
SIMS, A. P., School of Biological Sciences, University of East Anglia, Norwich, U.K.
SMITH, D. C, Department of Botany, University of Bristol, Bristol, U.K.
SMITH, H., Department of Physiology and Environmental Studies, University of Notting-
ham School of Agriculture, Sutton Bonington, Loughborough, Leics., U.K.
STEGWEE, D., Department of Plant Physiology, University of Amsterdam, The
Netherlands.
STEWARD, F. C, Cornell University, Ithaca, N.Y. and Department of Cellular and
Comparative Biology, State University of New York at Stony Brook, Stony Brook,
N.Y. 11794, U.S.A.
STEWART, W. D. P., Department of Biological Sciences, University of Dundee, Dundee,
U.K.
STREET, Η. E., Botanical Laboratories, School of Biological Sciences, University of
Leicester, Leicester, U.K.
SUTCLIFFE, J. F., School of Biological Sciences, University of Sussex, Falmer, Brighton,
U.K.
SYRETT, P. J., Department of Botany and Microbiology, University College, Swansea,
U.K.
TIMMIS, J. N., Department of Botany, University of Edinburgh, Mayfield Road,
Edinburgh, U.K.
WALKER, D. Α., Department of Botany, University of Sheffield, Sheffield, U.K.
WAREING, P. F., University College of Wales, Aberystwyth, U.K.
WILKINS, M. B., Department of Botany, University of Glasgow, U.K.
WIMBLE, R. H., Wye College, University of London, Wye, Kent, U.K.
WOOLHOUSE, H. W., Department of Plant Sciences, Baines Wing, University of Leeds,
Leeds, U.K.
PREFACE
The Fiftieth Anniversary of the inauguration of the Society for Experimental Biology
was celebrated by a special meeting held at the University of Cambridge from July 16th
to 19th, 1974. Prominent members of the Society were each invited to present a paper on
their own specialized field of research, providing a historical review, a statement of
current thought in that area and, if possible, a predictive element. In the belief that the
material thus presented would be of considerable use to other research workers, the
speakers were invited to contribute their papers to these two volumes. The chapters
therefore are each a personal affirmation, and reflect the approaches, opinions and styles
of their individual authors.
For convenience, the papers have been collected into one zoological and one botanical
volume. Within each volume papers on a particular discipline have been grouped
together, although these are not necessarily the groupings that were used when the papers
were read at the meeting. This perhaps underlines the difficulty of classification in such a
diversified field as is here presented. However, this diversity gives an indication of the
breadth of the Society's interests and of the topics which tend to appear most frequently
in its programmes. The diversity too, emphasizes the strength and aims of the Society; to
provide a forum for research workers in both animal and plant sciences to discuss
current research, to present work which is often still in progress and incomplete, and
above all, to encourage the cross-fertilization of ideas between specialized disciplines.
It is hoped that the material assembled in these two volumes will provide for young
research workers a perspective of the field of experimental biology and for under-
graduates a source of reference to a wide range of biological topics.
Several invited speakers were unable to provide a manuscript and we wish to record
our thanks to them for their contribution to the Anniversary meeting. We are also
indebted to those distinguished members of the Society who acted as chairmen to the
sessions of the meeting. They were: T. Weis-Fogh, R. Brown, G. M. Hughes, A. Punt,
P. W. Brian, Sir Vincent Wigglesworth, J. Chayen, R. D. Keynes, F. R. Whatley,
E. W. Simon, G. E. Fogg, J. Heslop-Harrison, J. W. S. Pringle, Sir Rutherford
Robertson, J. S. Kennedy, L. C. Beadle, D. A. Boulter, G. P. Wells, J. D. Robertson and
Helen K. Porter. Finally particular thanks are due to the local organizing team: Helen
Skaer, D. A. Hanke, C. G. Gill and the able Local Secretary, D. B. Sattelle.
Ν. SUNDERLAND, P. SPENCER DAVIES,
John Innes Institute, Department of Zoology,
Colney Lane, The University,
Norwich, U.K. Glasgow, UK.
xin
IN PRAISE OF EXPERIMENTS
Ο. V. S. HEATH
10 St. Peter's Grove, London, U.K.
IN THIS paper I propose to air my prejudices in favour of experimental science as com-
pared with non-experimental, or observational, science. At this 50th Anniversary Meeting
of the Society for Experimental Biology I may hope to be, in the main, preaching to the
converted. In fact, most of what I have to say will probably be considered trite—and the
rest no doubt wrong-minded.
If the Society had been formed say five years earlier I might well now be a zoologist.
As it was, just nine months before the birth of the Society in December 1923, I visited
my zoology professor at Imperial College, Professor MacBride, to tell him that I wanted
to transfer from zoology to botany. He said that he could not conscientiously recom-
mend anyone to take up zoology, as the prospects of employment were almost nil. In
fact those prospects were not the reason for my decision, but I did not feel it was necessary
to tell him that the main reason was that elementary zoology, as then taught at Imperial
College, consisted entirely of anatomy and morphology, with the promise of embryology
to come. We did not of course carry out any experiments in practical classes and the only
ones I can remember being told about were Kamerer's experiments on the nuptial pads
of the midwife toad—alleged to prove the inheritance of acquired characters.
In botany, which we did on days alternating with zoology, Professor Farmer did his
best to undo the harm done by MacBride and assured us of the impossibility of acquired
characters being inherited, but of more interest to me, the practicals included a course in
plant physiology when we carried out a number of intriguing experiments. I do not think
we were explicitly called upon to consider why we did these experiments, or, for instance,
that they tested predictions arising from hypotheses, but they were certainly great fun.
Nor did the fact that some of them were not exactly new detract from my enjoyment.
For example, we repeated some of the experiments on root pressure devised by Stephen
Hales (1727). We used manometers attached to the stumps of rooted plants much as he
did. Hales himself knew quite well why he did these experiments: 'And since we are
assured that the all-wise Creator has observed the most exact proportions, of number,
weight and measure, in the make of all things; the most likely way therefore, to get any
insight into the nature of those parts of the creation, which come within our observation,
must in all reason be to number, weigh and measure.' His aim was, therefore, to justify
the ways of God to man—an appropriate activity for a clergyman.
Hales also took the view that it was not enough to 'number, weigh and measure'
natural objects in a state of nature (that is, natural history studies) but it was also
necessary to carry out experiments, for he wrote : 'For the wonderful and secret operations
of Nature are so involved and intricate, so far out of the reach of our senses, as they
1
2 Ο. V. S. HEATH
present themselves to us in their natural order, that it is impossible for the most sagacious
and penetrating genius to pry into them, unless he will be at the pains of analysing
Nature, by a numerous and regular series of Experiments; which are the only solid
foundation whence we may reasonably expect to make any advance, in the real know-
ledge of the nature of things.'
He realized, however, that although honest experimental data are enduring facts, there
is always some degree of uncertainty of interpretation : Ί have been careful in making,
and faithful in relating the result of these Experiments, and wish I could be as happy in
drawing the proper inferences from them.'
In the Botany Department at Imperial College there was a great deal of experimental
research going on, both in Plant Pathology under William Brown and in the Research
Institute of Plant Physiology under V. H. Blackman, and when I became an Assistant
Demonstrator (on a salary of £225 p.a.) I began investigations on my own account. Later
I was seconded to work at Rothamsted, to fill the gap between the departure of Maskell
for Trinidad and the arrival of W. O. James appointed in his place. I was fortunate to be
at Rothamsted at a time of great intellectual excitement, shortly after the publication of
R. A. Fisher's (1925) Statistical Methods for Research Workers. This soon became my
bible—like the fundamentalist's bible everything was there, if only one could understand
it.
Fisher was a founder member of the Society and a member of its first Council. He
probably, in my view, did more for experimental biology than any other one person in
this century, especially by placing experiments with small samples on a sound basis, but
also by providing methods for analysis of factorial experiments which provide inform-
ation on how factors interact in aifecting biological material; information that is un-
obtainable in any other way.
He was a great believer in the experimental approach. Many years later F. G. Gregory
and I went to consult him about a problem. We were interested in the possibility that the
cells in apical growing points were 14-sided tetrakaidodekahedra, as suggested by
D'Arcy Thompson (1917), that being the space-filling solid nearest to a sphere and there-
fore of minimal surface, implying the predominance of surface tension forces. There
are no intercellular spaces in the growing point and therefore the shape of the cells must
be one that fills space in close packing. It seemed to me that assuming they were tetra-
kaidodekahedra it should be possible to predict the frequencies of triangles, quadri-
laterals, pentagons, hexagons etc. as seen in sections of the growing point, but of course
I was quite unable to do so. Fisher received us with a most benign and gracious con-
descension, and after brief consideration of the problem, he suggested that I should
prepare large numbers of plasticene tetrakaidodekahedra, cut them in random planes
and see. He then allowed us to feel that the interview was at an end—we felt we ought
really to walk out backwards.
During the War I was privileged to share a room in the Imperial College Laboratory
at Rothamsted with F. J. Richards. In one of our many discussions I put forward a view
very much like that which I have quoted from Stephen Hales (whose book I had not
then read), namely that without experiments it was impossible to arrive at an under-
standing of how things worked and that any so called science that did not involve
experiment was not a science at all but stamp collecting. Richards, who was a keen
3
IN PRAISE OF EXPERIMENTS
amateur astronomer, mildly enquired if I thought astronomy was a science and I had to
admit reluctantly that perhaps it was. After a good deal of thought I came to the con-
clusion that in Observational Science there were experiments, but they were provided by
Nature, who on the whole designed them very badly, and generally carried them out in a
slip-shod manner. A formal scheme for such Observational Science is shown in Fig. 1.
Recently (Heath, 1970) I suggested the following definition of science: 'Science consists
essentially in an attempt to understand the relations of selected aspects of things and
events in the real world, an attempt which should have both intuitive and logical com-
ponents, and which must be based on observation and tested by further observation.'
This definition of course excludes mathematics, which does not have to be based on
observations (data) but only on postulates which need not have any relevance to the real
world. It consists of a number of systems of logic, written in shorthand, and it can be
used to study relations in isolation, without reference to things or events. To the scientist,
mathematics makes up an important part of the tool-kit of techniques that he must use
but in my view it is not in itself a science.
I still believe in my definition of science and it implies that all science must begin with
observation of things in the real world and what they do (i.e. events)—that is it must
begin with natural history (1). For the observational scientist such natural history observ-
ations have two functions: first, exciting his interest and suggesting a problem for
scientific investigation, and secondly, providing part of the data for one of Nature's
experiments. These two functions may of course be filled by different sets of observations.
The next two stages are: (2) to make a hypothesis to account for the feature of the
observations that has excited interest and (3) to predict certain consequences of the
hypothesis which should be observable under specified natural conditions if it is true but
which have not yet been observed. For the next stage (4) it is necessary to wait for the
specified natural conditions to occur, and this may involve long delay or even going to
another part of the world. For example, one might have to wait for a different season
and/or go to a different latitude in order to test a hypothesis that flowering of a plant or
mating behaviour of an animal was a response to a particular photoperiod. The con-
trasting natural conditions for the initial observations (1) and the final ones (4) constitute
I. Observation under
la. Literature
'natural' conditions
/ (observations «
and hypotheses)
Disproof or
2.Hypothesis
support of 2
4. Further observation
3. Prediction under 'natural' conditions
and comparison with I.
FIG. 1. Formal scheme for the stages in non-experimental science. For explanation see text. (After Heath,
1970).
4 Ο. V. S. HEATH
the experimental treatments provided by Nature, but as (1) and (4) are usually widely
separated in time and often in space also, there are manifold changes of other conditions
confounded with the one that is intended. Thus at different latitudes or in different
seasons, not only daylength but also light intensity and temperature (to mention only
two other factors) will be different and it is virtually impossible to separate their effects.
The organisms studied will also be of different populations, for all biological material
changes with time and usually from place to place also. For a valid and unbiassed
experimental comparison, each individual in the population studied must have an equal
chance of being subjected to any one of the experimental treatments, but with 'treatment Γ
applied initially to one whole group of individuals and 'treatment 4' later to another
this cannot hold. The experiment is badly designed.
However, if the further observations agree with the prediction this can be held to give
some support to the hypothesis, while if they do not it may (sometimes) provide disproof.
Statistical tests of significance are not very meaningful in such natural experiments. To
use them would be rather like testing the significance of a difference in mean height
between samples of inhabitants of England and France. The test might show that the
English were 'really' taller, with a certain level of probability, but we should not know
whether to attribute this to the climate, or genetics, or the fact that the French eat frogs.
Fig. 2 shows the corresponding formal scheme for Experimental Science. The observa-
tions under natural conditions (1) now have only the one important function of exciting
interest and suggesting problems for investigation. The investigator can of course make
use of someone else's observations as recorded in the literature (la) but not only does
using his own observations give him more emotional drive to sustain him in the frightful
labour of trying to think connectedly and logically, it also enables him to collect data of
just the sort he wants—which the literature never provides.
He next has to think of as many as he can of the multitudinous hypotheses (2) that
might provide the explanation for the problem raised by the observations, and select the
one that most appeals to him. Again, someone else's hypothesis may be taken from the
literature, but I think his own hypothesis (by definition a good one) and the hope of
I.Observation under
la. Literature
'natural' conditions
(observations
and hypotheses)
Disproof or
2.Hypothesis support of 2
4. Experimental
3. Prediction comparisons
^(observations
under 'controlled'
conditions )
Design of
experiment New problems
FIG. 2. Formal scheme for the stages in experimental science. For explanation see text. (After Heath,
1970).
