G. Carington Purvis qualified as Bachelor of Medicine (MB) and Master in Surgery (Mast. Surg.) at the University of Edinburgh in 1882. After further studies at the same university he obtained the degrees Bachelor of Science (BSc) in Public Health in 1887, and Doctor of Medicine (MD), with Honours, in 1889. For some time he worked as senior assistant in zoology at the University of Edinburgh, and during 1890-1897 wrote five papers, including "Note on certain terminal organs resembling touch-corpuscles or end-bulbs in the intra-muscular connective tissue of the skate" (1890), "On the pineal eye of Lamna cornubica, or Porbeagle shark" (1893), and "Note on muscle fiber, electric disc, and motor plate" (1897). He retained an interest in the natural sciences throughout his career.
In March 1897 Purvis was appointed medical assistant to Dr A. Edington* at the Colonial Bacteriological Institute in Grahamstown. He was licensed to practice medicine at the Cape on 14 August that year. He was a brilliant and original man and for the rest of his career concentrated mainly on bacteriology. During 1899 he did a blood investigation for veterinary surgeon J. Spreull* and found intra-corpuscular parasites, resembling those of redwater, in the blood of a dog suffering from biliary fever (Canine Pyroplasmosis). He was the first to detect these organisms. The findings by him and Spreull were confirmed by W. Robertson* in 1901. He also found six types of micro-organisms in the blood of horses suffering from horse-sickness and described them briefly in "Horse-sickness micro-organisms", in the Agricultural Journal of the Cape of Good Hope in 1900 (Vol. 16, pp. 671-672). In 1902 he published a paper on "Some South African animal diseases" in the Proceedings of the Scottish Microscopical Society wherein he described some local stock diseases and attempted to indicate their causes. This work probably stimulated Edington in his attempts to correlate various stock diseases, and also stimulated the veterinarian Thomas Bowhill*, who studied the stock diseases of the coastal districts of the Eastern Cape.
In 1904 Purvis was president of the Eastern Province (Grahamstown) branch of the British Medical Association. At one of its meetings he demonstrated larval ticks from Kowie, and referred to piroplasma introduced by ticks that cause Rocky Mountain spotted fever. About that time he contributed "Notes on the etiology of cancer" to the South African Medicao Record (1903/4, Vol. 1, pp. 139-140). His other activities included an unpublished paper on "Some researches in the platinum group of metals", delivered at the annual congress of the South African Association for the Advancement of Science, held in Grahamstown in 1908.
In 1912 Purvis was appointed medical officer of health for Grahamstown, holding this position until the end of 1921. During this period he still did bacteriological work in private. Though he did well in public health, he never took kindly to the practical work of sanitation. In 1916/7 he became a foundation member of the South African Biological Society. During the last years of his life he suffered from heart disease, which rendered him an invalid a few months before his death. He was married to Cecilia M. Stark.