Blackman, Frederick Frost

(b. Lambeth, England, 25 July 1866; d. Cambridge, England, 30 January 1947)

plant physiology.

Blackman, whose father was a doctor, was the third child and eldest son in a family of eleven children. His interest in botany may have been started by a set of Sowerby’s British Botany that belonged to his book-collecting father; it developed during his school days at Mill Hill, where he started a herbarium. His interest in the plant as a whole remained throughout his life. On leaving school in 1883, Blackman entered St. Bartholomew’s Hospital to train as a doctor. Although his studies were highly satisfactory—he graduated B.Sc. in 1885—in 1887 he accepted an opportunity to read science at St. John’s College, Cambridge, where he shared rooms with his younger brother, later Professor V. H. Balckman, in 1895 he was elected to fellowship of his college, which he retained until his death. Blackman played an active part in the life of St. John’s where he lived until his marriage in 1917, holding the office of steward from 1908 to 1914. As an undergraduate his interests included music and pictures, and the college later benefited from his advice in aesthetic matters.

Blackman was appointed a university demonstrator in botany in 1891, and continued as a member of the botany school until he retired from his readership in 1936. He assumed a full share of the administrative work of the department, including the extension of the buildings in 1933. Everything he did was done with meticulous care, and he inspired others to do likewise. When, in recognition of the active school of plant physiology that he had developed from the basis laid down by his predecessors S.H. Vines and Francis Darwin, a subdepartment of plant physiology was created in 1931 with the aid of a grant from the Rockefeller Fund, Blackman naturally became its head and, but for technicalities regarding retirement age (resulting from the university statutes of 1926), he would have become the first professor of plant physiology at Cambridge.

Blackman was elected a fellow of the Royal Society in 1908 and was awarded a Royal Medal in 1921. Outside the botany school he served the university in various ways, including many years as a member of the Fitzwilliam Museum Syndicate. From 1901 to 1936 he was a member of the board of the Cambridge Instrument Company, which was started by Horace Darwin, brother of Francis, who had preceded Blackman as reader in botany.

Blackman’s published papers are not numerous. Although his mind was quick, he was not hurried over the planning of his experiments and the devising and perfecting of the apparatus; neither was he hurried in the contemplation of the results and the search for a just interpretation of them. He took great pains over the preparation of a paper; such was the standard he set himself that several papers, which in 1935 had reached a stage that would have satisfied many, were not published until after his death. Many papers by pupils in his laboratory bear his stamp if not his name.

Blackman’s first two botanical papers appeared in the Philosophical Transactions of the Royal Society in 1895. They began a series entitled “Experimental Researches in Vegetable Assimilation and Respiration,” which was continued by him and his puplis until 1933. As early as 1832 it had been suggested that most of the gaseous exchange between the leaves of a plant and the surrounding atmosphere takes place through the stomata. For a long time this was much disputed, and it was not accepted until convincing experimental evidence was produced by Blackman. The first paper described an apparatus for measuring the carbon dioxide in gaseous mixtures, of which Blackman said, “The raison d’être of the apparatus is to be found in the perfection of details and their adaptation so that all the various processes can be performed with the minimum of error, time, and labor”(p. 487). This approach characterized all his designs.

Blackman was surprised by the high rate at which gases diffused through a septum with many small holes, as compared with that when there were fewer holes with the same total area. His correspondence with his friend R. A. Lehfeldt, a physical chemist, shows that the latter advised him that “The effectiveness of a stoma should be proportional to its diameter but if the stomata were very close more nearly proportional to the area.”

In 1904 the third paper in the series, by Blackman’s pupil G.L.C. Matthaei, demonstrated that temperature had little effect on the rate of carbon assimilation at low intensities of illumination, while at high intensities the effect was comparable with that of many chemical reactions. This work directed Blackman’s thoughts along lines that resulted in the publication of his classic paper “Optima and Limiting Factors” (1905). The terms “limiting factor” and “bottleneck” were not on the lips of biologists at that time. This paper is that of a pioneer in the application of physicochemical ideas to biological problems, a pioneer not unaware of the complexities of such problems. For instance, he says, “Physico-chemical finality is not to be attained in this matter, but special research might at least show how far the recorded optima are real metabolic truths and how far they are illusions of experimentation” (p. 286), and continues “…at present our science entirely lacks data that will stand critical analysis from the point of view indicated” (p. 295). The process limiting the rate of carbon assimilation at high intensities of illumination was later named the Blackman reaction by Otto Warburg.

These ideas were developed further in Blackman’s presidential address to the Botany Section at the British Association meeting in 1908. It was a bold action to plead for the consideration of vital processes from the point of view of laws governing physicochemical processes at a time when, as he said, in consequence of the teaching of Pfeffer, “The notion that every change in which protoplasm takes part is a case of ‘reaction’ of an ‘irritable’ living substance to a ‘stimulus’ overflowed its legitimate bounds and swamped the development of physical-chemical concepts” (p. 2), and continued, “No general treatment of the physiology of plants had yet been attempted in terms of reaction velocity” (p 17).

Blackman later turned his attention to plant respiration. In 1928 three papers appeared dealing with part of the investigations his pupil P. Parija had made on the effect of the partial pressure of oxygen on the production of carbon dioxide by apples. Other papers were published with the assistance of a former pupil, J. Barker, after death. The third paper of 1928, under Blackman’s name, gives his interpretation of the complicated set of results analyzed in the previous papers. On the assumption that the of glycolysis underwent fermentation to carbon dioxide and alcohol or complete oxidation to carbon dioxide and water, he deduced that glycolysis in air is more nearly complete than in nitrogen. Because the production of carbon dioxide in nitrogen was much more than one-third of that in he concluded there must be yet another fate for the products of glycolysis, which he called “oxidative anabolism.”

His typical conclusion was that this schema provided a “plausible interpretation of all the quantitative variations of CO₂ production observed” (p. 521); yet other data awaited similar analysis, “after which it may become necessary to take the present schema to pieces and reconstruct it…, but at least we shall have consolidated a mass of relations to which any future system must conform” (p. 522). This conclusion was based on an analysis of the behavior of more than twenty individual apples. Under Blackman’s guidance his pupils carried out investigations on sugar content, rate of oxygen consumption, and composition of the atmosphere in the intercellular spaces of apples, in an attempt to complete the respiratory picture for this plant organ. Unfortunately, the work did not progress further than doctoral theses, now in the University Library at Cambridge.

Blackman’s interests in botany were not confined to plant physiology. In his early years he lectured on the algae and later, with A. G. Tansley, his future brother-in-law, published “Classification of the Green Algae” in the first volume of the New phytologist (1902). His other contribution to biology-certainly not the least-was the effect he had on many who attended his lectures. These were works of art, appreciated more on a second hearing, which they received from many of his research students. A mass of data collected from his wide reading or his own experiments was marshaled to point to his interpretation. The full discipline of Blackman’s ways was experienced by those who had the privilege of starting research under his guidance. These students, many of whom proceeded to leading posts in British botany, carried the torch he lit.

BIBLIOGRAPHY

I. Original Works. Blackman’s writings include “Experimental Researches in Vegetable Assimilation and Respiration. I. On a New Method for Investigating the Carbonic Acid Exchange of Plants. II. On the Paths of Gaseous Exchange Between Aërial Leaves and the Atmosphere,” in Philosophical Transactions of the Royal Society, B186 (1895), 485–562; “III. On the Effect of Temperature on Carbon-dioxide Assimilation,” ibid., B197 (1904), 47–105 (by G. L. C. Matthaei); “Optima and Limiting Factors,” in Annals of Botany (London), 19 (1905), 281–295; “The Manifestations of the Principles of Chemical Mechanics in the Living Plant,” in Transactions of Section K of the British Association Meeting (London, 1908), pp. 1–18; “Analytic Studies in Plant Respiration. I. The Respiration of a Population of Senescent Ripening Apples [written with P. Parija]. II. The Respiration of Apples in Nitrogen and Its Relation to Respiration in Air [by Parija]. III. Formulation of a Catalytic System for the Respiration of Apples and Its Relation to Oxygen [by Blackman alone],” in Proceedings of the Royal Society, B103 (1928), 412–513; and Analytic Studies in Plant Respiration (Cambridge, 1954).

II. Secondary Literature. Articles on Blackman are G. E. Briggs, in Obituary Notices of Fellows of the Royal Society, 5 (May 1948), 651–657; and Dictionary of National Biography, supp. for 1941–1950.

G. E. Briggs