During the years 1926 to 1933 inclusive, the lungs of 4,910 diseased South African miners and native laborers were examined by the authors. This number includes many persons who in life suffered from varying degrees of silicosis. The objective of the investigation was to develop evidence relative to a controversy, the points of issue of which are here taken from the authors' introduction.
"Can the nodular fibrosis which is recognized as the characteristic lesion in silicosis be produced as a simple response of the lung tissue to the presence of silicious dust?" or
"Is an element of tuberculosis always necessarily present in the original development of the lesions?"
The accumulated evidence is grouped into three sections, designated by the authors respectively as "The Histology of Silicotic Lesions from the Lungs of Diseased Gold Miners," "Results of Inoculation into Guinea-Pigs of Silicotic Lesions from the Lungs of Deceased Gold Miners," and