MacMunn, Charles Alexander (1852–1911), doctor, army officer and physiologist, was born 11 April 1852 at Seafield House, Easky, Co. Sligo, the home of his father Dr James MacMunn, medical officer to the Easky dispensary and the Dromore West Union workhouse. After attending Dromore school, Co. Sligo, he entered TCD in November 1867, graduating BA (1871), MB (1872), MD (1875) and MA (1884); he was also a licentiate of the RCSI (1872). As a student at the Meath Hospital (1870–71), MacMunn jointly won the 1872 Hudson prize for medical cases, was joint second in the 1872 medical prize, and served as one of two clinical clerks there (April–October 1872). MacMunn studied under William Stokes (qv) (d. 1878), the doyen of the golden age of clinical instruction and research in Dublin, who encouraged him to study spectroscopy. The Cambridge physicist George Gabriel Stokes (qv), William's cousin, had demonstrated haemoglobin's oxygen-carrying capacity in an 1864 paper, elemental in physiology and nascent biochemistry for demonstrating the respiratory function of haemoglobin. Both Stokeses greatly influenced MacMunn's interest in spectrographic research.
MacMunn joined the medical practice of his cousin James MacMunn, at 17 Waterloo Road, Wolverhampton, England, in early 1873; upon the latter's death (November 1873) Charles took over the practice. He married James's daughter Laetitia (b. 1850) on 20 January 1874 and they had at least three sons (Verian, Lionel and Norman). Later moving to Oakleigh, Oaks Cescent, Merridale, Wolverhampton, MacMunn had a thriving practice by the early 1890s. From his appointment in 1877 as a surgeon-captain in the 3rd battalion of the Staffordshire Regiment, Army Medical Reserve, he remained deeply involved in volunteer military medicine.
MacMunn served as medical officer, and later as physician and honorary pathologist, to the Wolverhampton general hospital, and was surgeon, and later honorary consulting physician, to the Royal Orphanage of Wolverhampton. Alongside his personal practice and consulting roles, MacMunn undertook extensive spectroscopic research in the laboratory he established in the loft over his stables, with funding from the Royal Society and the Birmingham Philosophical Society. A spy-hole enabled him to ward off unwanted visitors as well as professional and social distractions; his housekeeper was instructed to turn callers away. His early experiences in clinical medicine and his experiments identifying and mapping the absorption spectra of blood, bile and urine were published in the Dublin Journal of Medical Science (1876–80). Often spending his summer holidays working at the marine biological laboratory in Plymouth, MacMunn undertook marine biological research, especially in the pigments of deep sea organisms, Crustacea and corals.
Immersing himself in physiological spectrographic research, in the richly illustrated The spectroscope in medicine (1880) MacMunn argued such research would 'likely to be of almost as great use in medicine as it has already proved in terrestrial, solar, and stellar chemistry'. An important contemporary text, it described his experiments into the absorption bands of various mammalian tissue, a new approach to the study of biological oxidants operation in respiration. Examining a variety of tissues in animals drawn from almost every phylum, communicating with leading international colleagues while staying abreast of the emerging literature, MacMunn identified a distinct absorption spectrum emitted by a pigment found in various muscles and tissues. By using a small spectroscope in place of the eyepiece of a microscope, MacMunn identified four colour bands that varied by limiting the air supply. Surmising that these natural pigments were integral to respiration, MacMunn addressed the long-standing debate about whether respiration took place in tissues or the lungs. On 13 December 1884, in a paper delivered to the Physiological Society in London, he identified 'histohaematins' (tissue pigments) and 'myohaematins' (muscle pigments) as integral to cellular respiration; MacMunn published this work in the Philosophical Transactions of the Royal Society (vol. clxxvii, 1886) and the Journal of Physiology (1887).
However, MacMunn's findings concerning these newly identified compounds were not accepted by the distinguished German physiologist and chemist Felix Hoppe-Seyler (1825–95), who in 1862 had described the absorption spectrum exhibited by the red pigment in blood, which he named haemoglobin. Hoppe-Seyler claimed that MacMunn's work was unverifiable and therefore mistaken, and attributed MacMunn's findings to poor experimental technique leading to the mere observation of the breakdown products of haemoglobin. MacMunn responded (1889, 1890) to specific criticisms in the Journal for Physiological Chemistry (Zeitschrift für Physiologische Chemie), founded and edited by Hoppe-Seyler, but the criticism of such an eminent figure was enough to sideline MacMunn's work, and his putative discovery of the respiratory pigments went unrecognised in his lifetime. Although partly due to MacMunn's own inability (and that of contemporaneous science) to attribute and explain their complex absorption spectrum, Hoppe-Seyler's arrogant denunciation ensured MacMunn's foundational work was ignored, and discouraged him from undertaking further research; he noted: 'Hoppe-Seyler has prevented the acceptance of the writer's views. The chemical position is undoubtedly weak, but doubtless in time this pigment will find its way into the text-books' (MacMunn, Spectrum analysis, 72–3).
MacMunn's work was, however, vindicated by later research. The University of Cambridge entomologist David Keilin (1887–1963) demonstrated in 1924 that the spectra identified by MacMunn were attributable to not one but three pigments: Keilin named these three cytochromes (a, b, c). The respiratory pigment, cytochrome, is present in all living cells and is integral to respiration, absorbing oxygen and producing carbon dioxide. Explicitly crediting and confirming the validity of MacMunn's original insight into the importance of the histohaematins, Keilin established that MacMunn's pigments were integral in intracellular oxidation and therefore respiration. The considerable advances in biochemistry in the intervening decades had yielded much new relevant knowledge, and in a 1964 monograph Keilin contextualised MacMunn's insightful research, the opposition he met, and how his 1924 rediscovery was better placed to explain MacMunn's earlier insight.
MacMunn volunteered as an administrative medical officer in the South African war (1899–1902) and served as a surgeon-major in the Army Medical Reserve. Working with Lady Roberts, wife of the commander-in-chief of British forces, Field-Marshal Frederick Sleigh Roberts (qv), he oversaw four wards at a medical hospital in Bloemfontein (February–July 1900), combating the serious typhoid (enteric) outbreak there. He then moved to Pretoria as medical officer to the Bourke hospital, and was seconded from Lord Roberts's staff to the royal commission on South African hospitals (1900–01), to which he also gave evidence (August 1900) in South Africa. He also gave evidence to the house of commons select committee on the registration of nurses in 1904.
Active in scientific, medical and volunteer associational life, MacMunn was a member of the Physiological Society and the Marine Biological Association, and a fellow of the Chemical Society and the Royal Physiological Society of Edinburgh. A regular contributor to Nature, he published Outlines of clinical chemistry of urine (1889) and wrote on the chemistry of animal colours for the Encylopedia Britannica (1911); his Spectrum analysis applied to biology and medicine was published posthumously in 1914.
MacMunn founded a branch of the RAMC (established 1898 and reconstituted in the aftermath of the South African war) in Wolverhampton, serving as colonel commandant until 1907. Awarded the Edward VII Coronation Medal (1902) and the Volunteer Officers' Decoration (1907), he was a JP for Staffordshire from 1907 and a life governor of Birmingham university. He retired as brigade surgeon-lieutenant-colonel in the Staffordshire Volunteer Infantry Brigade and administrative medical officer of the North Midlands Division of the Territorial Force of the British army in 1909. Continuing to suffer from malarial symptoms he first caught in South Africa, he retired from his various medical commitments in 1909, and died at home in Wolverhampton, 18 February 1911. His funeral took place 23 February at St Peter's church, Wolverhampton, with full military honours; his coffin was carried through Wolverhampton on a gun carriage to be buried in Penn cemetery, Wolverhampton. MacMunn married secondly Susan Bartlett (née Webb) (d. 1942), a sister of Captain Matthew Webb (the first person to swim the English Channel). His son Norman MacMunn (1877–1925) was a noted educationalist; his cousin James Robert McMunn (1866–1945) was a distinguished medic in the RAMC.