OBITUARY : Professor O. V. S. Heath

O. V. S. Heath was a biologist who made seminal contributions to our understanding of how plants grow and function. His influence did, however, extend far beyond his own discipline of plant physiology because of his wide interests in the methods of experimental science.

In the preface to his little book Investigation by Experiment (part of Edward Arnold's "Studies in Biology" series), published in 1970, at the end of his active career, he wrote:

. . . it is of the utmost importance that everyone should have some understanding of the nature, potentialities and limitations of science, also that we can only obtain this by carrying out original experiments ourselves. The methods of science are available to anyone for the solution of practical problems and the discovery of new knowledge in everyday life, but until this is generally realised and acted upon there will be little real understanding of science.

He used to tell his students that, although experiments do sometimes fail for technical reasons, more often than not the failed experiment is the result of unclear thinking at the design stage: "To design and carry out a good experiment and to consider the result requires an exacting mental effort, often for long periods."

Heath is now best remembered for his studies of stomata, the little pores on the surfaces of leaves that permit the intake of carbon dioxide from the atmosphere and thus regulate the vital process of photosynthesis. His distinguished contributions to this subject led to his election as a Fellow of the Royal Society in 1960. When asked why he had devoted so much of his scientific career to what was then an obscure corner of plant physiology, he used to say that early in his career he was advised to find a topic that everyone thought was "sewn up" and then seek aspects that had been overlooked.

Perhaps his most important contributions were his meticulous studies of the responses of stomata to the carbon dioxide concentration of the atmosphere. He laid a foundation for our present understanding of one of the main consequences of the pollution of the Earth's atmosphere.

The rise in the carbon dioxide concentration, from around 280 parts per million in pre- industrial times to a value of nearly 360 today not only affects the climate via the "greenhouse" effect, but also causes the stomata of many plants to close partially. This alters the rate of transfer of water from the soil to the atmosphere, and it also affects the surface- atmosphere exchange of heat and contributes to global warming. Thus the ability of stomata to sense and respond to carbon dioxide in the atmosphere, once thought to be an obscure topic only of academic interest to Heath and a few other scientists, has become a major factor in our understanding of the forces that are driving climate change.

Today, priority is being given to science of immediate or foreseeable practical value, and most young scientists of the present generation are denied the free choice of a topic for study that was Heath's privilege.

In the 1950s and 1960s great advances were made in understanding the chemistry of photosynthesis, the process on which all life on Earth ultimately depends. It was a brave decision by Heath to publish, as late as 1969, a book entitled The Physiological Aspects of Photosynthesis which omitted nearly all the recent advances in chemistry, and concentrated on what he said was the principal role of the physiologist: "To assist the biochemist and physical chemist with information as to how the systems studied operate in various environmental conditions, especially those in which the organisms normally exist".

It is important to remember where and when he wrote these words. In 1958 he had moved from Imperial College, London, where he was a Reader in Plant Physiology, to Reading University, where he became Professor of Horticulture. Here, all the department's research was carried out at Shinfield Grange, a country house surrounded by attractive gardens used for teaching ornamental horticulture to undergraduates, and with extensive greenhouse facilities for research.

This gave him a splendid opportunity to indulge in his love for experimentation, growing plants on a much larger scale than was possible in the cramped conditions available to most plant scientists at that time. Very quickly, Reading became a major centre for plant physiology, and eminent visitors from the United States and elsewhere were often to be seen strolling in the gardens immersed in scientific discussions.

In 1961 the Agricultural Research Council decided to locate a special unit of Flower Crop Physiology at Shinfield Grange, and Heath became its director while he continued as head of the horticulture department. Thus began a period of real distinction in research at Reading, and long after his retirement Heath was pleased to see the continuing success of his former department, most recently the five-star rating for research quality in 1996.

Outside science, Peter Heath played the flute and sang in choirs, and one of his principal interests later in life was country dancing. He claimed he knew nothing of its attractions until one evening at Imperial College. He was working late in his office and was disturbed by the sound of music and merriment from a floor below. He went downstairs to make an angry complaint, but was so fascinated by what he saw that he joined in. He fell and broke a hip at the age of 89, but he was so determined to return to his physically active life that his recovery amazed his doctors and he was able to resume his country dancing within six months, continuing until only a few weeks before his death.

From 1955 to 1973 Heath was a council member and treasurer of the Society for Experimental Biology, and he saw it grow from a small membership based mainly in the UK to a large organisation of international importance which today has over 2,000 members. He is warmly remembered within the society for his lively contributions to debates, and for the advice and encouragement he gave to young scientists.

Yet, during his own career, his beloved stomata remained a minority interest and the society never enabled him to organise a special session on stomatal physiology. The position has changed dramatically in recent years, and in April 1997 the society included a three-day symposium entitled "What Are Stomates For?" in its annual meeting at the University of Kent, with contributions from the United States, Australia and many other countries.

Peter Heath was not able to attend, but he sent warm greetings to the participants, saying, "I am glad to see that the vital importance of stomata is now acknowledged by the society, but I do deplore the use of the term `stomates' - a dreadful example of the Americanisation of our language!"

Oscar Victor Sayer ("Peter") Heath, plant scientist: born London 26 July 1903; Assistant Demonstrator in Botany, Imperial College, London 1925-26, Research Student 1936-39, Leverhulme Research Fellow 1937-39, Special Lecturer in Plant Physiology 1946-58, Senior Principal Scientific Officer 1948-58; Empire Cotton Growing Corporation Senior Student, Imperial College of Tropical Agriculture, Trinidad 1926-27; Plant Physiologist, Empire Cotton Growing Corporation Cotton Experiment Station, Barberton, South Africa 1927-36; Research Assistant, Research Institute of Plant Physiology, Imperial College, Rothamsted 1939-40, staff 1940-46; Professor of Horticulture, Reading University 1958-69 (Emeritus); FRS 1960; Director, Agricultural Research Council Unit of Flower Crop Physiology 1962-70; Leverhulme Emeritus Research Fellow 1970-72; married 1930 Sally Bumstead (died 1984; two sons, one daughter); died London 16 June 1997.