The morbid anatomy and histology of the essential lesion of tuberculosis have long been known, and while sixteen years have elapsed since Koch's discovery of the specific parasite of tuberculosis, still, in the face of a vast amount of study, many questions relative to the source, the conduct and the fate of the elements of the tubercle remain unanswered. The giant cell of the tubercle—that prominent and well-known object —what is its origin and its destiny? The genesis of this element is still unknown; indeed, it is a point upon which such brilliant investigators as Langhans, Baumgarten, Weigert, Koch and Metchnikoff hold diverging opinions.
In the progressive and destructive form of tuberculosis the giant cell dies and becomes a part of the cheesy mass of necrotic material so evident in advanced tuberculous lesions. In case the destructive tendency of the infection becomes arrested from attenuation in virulence of the invading