EPIDIDYMIS: This organ not infrequently presents gross abnormalities, and very often is pathological on microscopic examination. Acute, inflammation, with induration or abscess formation, is very common in the tail, but less so in the head and body. Possibly this is caused by the fact that the tail is the most pendant portion of the organ. In these cases, the tail is enlarged, soft, and quite hot and painful on physical examination. Enlargement, due to a connective tissue induration, occurs occasionally in all three parts, and the inflammation may produce adhesions to the adjacent serous membranes. Inflammation of both the parietal and visceral layers of the tunica vaginalis is very common. In those cases, the membrane usually is quite hyperaemic, and on the surface it presents many small reddened tufts of newly-formed connective tissue. In adult bulls it is exceptional not to find at least slight evidence of some previous inflammation. In all of the numerous bulls examined, both apparently normal and sterile, I have found but one in which some evidence of inflammation (either present or past) could not be found. Along with the fibrous tufts, are numerous fine strands of connective tissues passing from the covering of the tail of the epididymis to the adjacent portion of the parietal layer of the tunica. The strands often extend even to the upper part of the head. Microscopically, inflammation of the part is shown by hyperaemia, loss of cilia of the lining cells, and exudation. In the more severe forms, the lining cells which furnish considerable secretion for the nourishment and stimulation of the sperms, become degenerated, and are exfoliated into the lumen, as in Fig. 21. This condition is very common in sterile bulls, and those of lowered fertility. In the chronic types, the interstitial connective tissue is increased in amount, leading to degeneration and atrophy of part or all of the tubules, as in the case of Bull 2. Infiltration with leucocytes, and necrosis, are the predominating lesions in the pyogenic types of inflammation. DUCTUS DEFERENS: This tube seems to be peculiarly free from severe inflammatory processes, and when these appear they are limited to the mucosa. The cells of the lining membrane not infrequently show a mild type of degeneration and exfoliation, or in the more chronic forms, the entire membrane degenerates and disappears. In man, the duct occasionally becomes occluded, but so far I have failed to find this condition in the bull. Undoubtedly, when the occlusion does occur, it is near the origin of the duct at the tail of the epididymis.