In the _nasal mucosa_ the bacilli form prolific colonies at different points of the membrane and submucosa with the active production of lymphoid cells, followed by granular fatty degeneration and ulceration. Hence may be found different lesions representing the different stages. First there may be miliary deposits with clear contents and standing out like grains of sand. Then there are the larger pea-like nodules with congested vessels and minute hæmorrhages, but made up largely of the nests of lymphoid cells. These may bear on the surface a distinct blood extravasation, or the epithelium may be raised from the corium layer by a liquid exudation. The more advanced nodules show the centre light colored, grayish or yellowish with a distinct granular degeneration of the cells. Later still the degeneration involves the superficial layers and epithelium and an open ulcer is formed with a strong tendency to extend in depth and width. The formation and degeneration of numerous foci of cell proliferation gives the ulcer a very uneven outline. The continuous growth of fresh centres of proliferation may cause marked elevations between the ulcers, constituting extended patches, or the entire nasal mucosa may be thickened as the result of the morbid deposit. The cicatrices resulting from the apparent healing of deep or extensive ulcers or from a fibroid, transformation of the neoplasm consist of condensed connective tissue with small scattered nests of lymphoid cells and bacilli. In chronic cases the bacilli are very scanty. The mucosa of the _Eustachian pouches and tubes, the larynx, trachea and bronchia_ often present lesions similar to those of the pituitary membrane. The _lungs_ are usually marked in chronic cases by circumscribed lobular pneumonia, interlobular and peribronchial inflammations and miliary or larger areas of degeneration resembling tubercles. These may begin as a minute congestion and ecchymosis, which later shows in the centre a translucent or gray mass of lymphoid cells, with a surrounding area of congestion. Later still this central mass becomes yellowish and caseated from granular and fatty degeneration and this gradually extends so as to involve the whole area of the nodule. The peripheral portion may condense into a fibroid envelope, but usually this is less smooth and evenly rounded than in the case of an inspissated abscess or bladder-worm. The bacilli are found in the affected tissue but not always abundantly.