In bovine pathology the term “Rheumatism” is applied to a number of different morbid conditions, the sole connection between which is that they seriously affect the organs of locomotion. This reason may perhaps be accepted as sufficient for including the study of rheumatism amongst diseases affecting locomotion. The disease is of considerable importance, and for this reason the study of rheumatism itself necessarily precedes the description of pseudo-rheumatism, secondary rheumatism, or infectious rheumatism in young and adult animals. ARTICULAR RHEUMATISM. Acute rheumatism has a clearly marked predilection for the articulations. Sometimes the great serous membranes are simultaneously affected (pleura, pericardium, endocardium), but only in very exceptional circumstances are they primarily attacked. That form of rheumatism known as visceral is as a general rule secondary in comparison with articular rheumatism. Several joints and tendon sheaths may be attacked at the same time. Under such circumstances rheumatism may be defined as a febrile disease, probably of an infectious nature, revealing itself by simple or multiple inflammation of joints and the tissues surrounding them, and capable of becoming complicated with inflammation of the pleura, pericardium, endocardium, meninges of the brain, etc. =Causation.= All authors agree in recognising the influence of heredity, of wet and cold, of sudden changes in temperature, draughts in the stable, prolonged exposure to low temperatures, or the chilling of animals saturated with perspiration. These are and cannot be otherwise than occasional causes; but the determining cause remains at present unknown. In human pathology it has been proved beyond dispute that a certain relationship exists between arthritism, or the “uric acid diathesis,” and rheumatism. This fact is so well recognised that doctors have said that rheumatism was to arthritism what scrofula is to tuberculosis. That, however, does not advance our knowledge of the question in the smallest degree, and it may simply be that arthritism represents one of the principal favouring conditions in the development of rheumatism. In domestic animals the uric acid diathesis is little known, renal lithiasis is no more a rarity than gravel; but at the present time no one appears clearly to have established the relationship between these diseases and the development of rheumatism. What, however, we must all admit is that rheumatism exhibits all the phases of development of a rapidly progressive infectious disease. Numerous attempts have been made by doctors during the last few years to discover the presence of a microscopic agent and to demonstrate its pathological characteristics. Several microbes have been described, but one is forced to confess that the results have until now been very contradictory and uncertain; and yet there is little room to doubt that the disease is of an infectious character.