Johnson was born in
Angaston, South Australia to
James Angas Johnson (1841 – 19 May 1902) and his wife Catharine Johnson, née Williams (1841–1909), who married in 1866. James Angas Johnson's mother, Rosetta French Johnson (25 April 1813 – 23 August 1898), later Hannay, was the eldest daughter of
George Fife Angas. The Johnsons owned a magnificent property, "St Catharine's" in
Prospect, later the administration centre of
Blackfriars Priory School. He was educated at
Whinham College in
North Adelaide,
St Peter's College, and the
University of Adelaide, but (with many others) was unable to complete the requirements of the Bachelor of Medicine degree in Adelaide because of the "Hospital Row", a toxic standoff between the
Adelaide Hospital and the State Government in the mid- to late 1890s, (see
Nurse Graham) and professional rivalries as exemplified by this exchange between Professor
Archibald Watson and Dr
Leith Napier, in which Johnson's name was mentioned. Hence, it was in Melbourne where he graduated in 1897, as did many others, or in Sydney, then took his
ad eundem at Adelaide. He served a year as house surgeon at the
Adelaide Children's Hospital, then went to Germany, where he gained his doctorate at the
University of Göttingen, and also studied at the Berlin University. In 1900 he worked at the
Pasteur Institute under Professors
Roux and
Metchnikoff. He continued gaining experience and qualifications at the
London,
King's, and
St Bartholomew's Hospitals. He studied at the
London School of Tropical Medicine, under Sir
Patrick Manson and Sir
James Cantlie, and afterwards to Cambridge, where he studied
preventive medicine with Professors
George Nuttall and
Sims Woodhead. He resigned a year later, in advance of another trip to Europe. In December 1907 he stood again for the same Ward, and was voted in by a large margin, holding the seat until he resigned in February 1924 as a necessary condition of being appointed Health Officer, a very senior position which also required him to resign his membership of the Adelaide Board of Health and its public health committee, of which he had been chairman for 14 years. He was skeptical about the effectiveness of
Pasteurella bacteria in the control of rabbits as proposed in 1905 by
Professor Danysz, and which had been elsewhere been greeted enthusiastically. He argued in 1937 against
diphtheria immunization on the grounds that it was effective against the milder forms of the disease but might promote the more dangerous
gravis strain. Concern was raised that his outspokenness might prompt parents to withdraw consent to a measure that had been proved both safe and effective. ==Other interests==