He was born on 17 April 1812 in Ayr to the Scottish physician David MaclaganFRSE, and Jane Whiteside. He was the elder brother of William Dalrymple Maclagan, who would become Archbishop of York; and of the engineer and soldier Gen Sir Robert Maclagan. His youngest brother was the eminent accountant, David Maclagan FRSE manager of the Edinburgh Life Assurance company. Douglas was educated at the Royal High School and the University of Edinburgh, graduating in 1833. He subsequently toured hospitals in London and in continental Europe with James Young Simpson. On his return to Scotland, Maclagan was appointed Assistant Surgeon at the Royal Infirmary of Edinburgh. He lectured on Materia Medica at the Extramural School of Medicine 1845-1862. Maclagan was a close friend of toxicologist Robert Christison, and he developed an interest in toxicology and forensic medicine. He was elected a Fellow of the Royal Society of Edinburgh in 1843, his proposer being Robert Christison. He served as their Curator 1856-1878, Vice President 1878-1890, and President 1890-1895. Maclagan was appointed to the Chair of Medical Jurisprudence and Public Health at the University of Edinburgh in 1862, retiring in 1897. This included some of the world's first lectures on Forensic Science. He died at home, 28 Heriot Row in Edinburgh on 5 April 1900. He is buried with his wife and children in Dean Cemetery on the west side of Edinburgh. He is buried in his father's plot, against the north wall of the original cemetery, backing onto the north extension.
Trials of Note
In his role both as a toxicologist and forensic scientist Maclagan gave evidence in many trials, including some very notable cases:
Junior assistant to Robert Christison in the medical evidence for the Burke and Hare trial
Affirmed the victim was poisoned by arsenic in the Madeleine Smith trial
Nugae canorae medicae: lays by the poet laureate of the New Town Dispensary
Family
Maclagan was married to Elizabeth Allan Thomson. They had twin daughters who died in infancy in 1842, plus a further infant daughter who died in 1850. A son, David Philip Maclagan, was a surgeon in the Royal Navy and died in Honduras in 1860, aged only 23. Nellie, their only surviving daughter, died in 1892 aged 48. His son Dr Robert Craig Maclagan FRSE was a prominent physician and anthropologist.
