In this investigation the hitherto unexplored field of tuberculous Lanarkshire has been surveyed.

The relative incidence of human and bovine strains of the tubercle bacillus in 80 cases of pulmonary tuberculosis and in 311 cases of extrapulmonary tuberculosis has been examined. Results have shown that bovine infections were present in 2·5% of the pulmonary cases, a figure that is in keeping with the expected incidence for an area as highly industrialized as Lanarkshire.

The extrapulmonary strains have been further subdivided into 165 strains isolated from patients suffering from tuberculous meningitis, 72 strains isolated from patients with cervical adenitis and 74 strains from patients with tuberculous lesions affecting bone or joint. Each group has been analysed separately.

In the 165 cases of tuberculous meningitis bovine infections accounted for 28·5 % of the total. This figure was slightly higher than the 22% given by Blacklock & Griffen (1935) for the Glasgow area and the 24% of Macgregor & Green (1937) for the Edinburgh area, but it was lower than the 36% found by Munro & Scott (1936) in the east of Scotland and the 40·5% given for Scotland by Griffith (1934) in his general survey. The greater preponderance of bovine infections in rural areas supported the observations of these workers.

The cervical adenitis group gave the percentage of bovine infections as 30·4, a result much lower than any previously published for Scotland, but there can be no doubt that a family history of pulmonary tuberculosis obtained from 50 % of the patients in the industrial group who supplied human strains must have been a most important factor in influencing the relative incidence of the two types of tubercle bacillus. There were 72 cases of cervical adenitis investigated and 52 came from the industrial area.

Seventy-four patients suffering from tuberculous lesions affecting bone or joint gave a bovine incidence of 18·9%, a percentage that is lower than that given by Munro & Cumming (1926) of 36·4% but approximating to the 20·5% given by Wang (1917) for the Edinburgh area. Munro & Cumming were dealing with a less industrialized area than Lanarkshire which probably accounts for the variation as also does the fact that, of 7 human cases occurring in the rural part of Lanarkshire, 5 gave a family history of pulmonary tuberculosis.

These figures only serve to substantiate observations of regional variation and endorse the findings of other workers who have found a lower proportion of bovine infections in industrial districts. As Lanarkshire is the most highly industrialized county in Scotland it was to be expected that the results of this investigation might have given an even greater predominance of human infection than actually was found.