ETIOLOGY.--Muscular rheumatism is a very common affection. All ages are liable to its occurrence, but the part affected varies with the time {75} of life, children and young adults being much more subject to torticollis, and older persons to lumbago and general rheumatism of the limbs. Amongst hospital patients the disease prevails more amongst men than women, owing doubtless to the greater exposure of the former to the cold; but amongst other classes the same difference is not seen. It is observed in all countries, but according to some writers it is unusually frequent in tropical climates, although there acute rheumatism is very uncommon. The causes of muscular rheumatism are mainly exposure to cold and strain or fatigue of muscles. If these two conditions coexist--_e.g._ standing in a draught of cold air or lying on the ground when fatigued--the chances of the affection coming are greatly enhanced. Strain, a twist of the body, or a false step can actively start an attack of this kind, and by the sufferers themselves it is constantly attributed to this cause. The part played by this element is difficult to determine, a very slight strain being often followed by great pain and distress from the subsequent rheumatic affection. Some individuals are specially prone to attacks, the slightest current of air, change of clothing, etc. being sufficient to determine its occurrence. These persons are often found to have suffered from rheumatism in some other form, and thus in them we must consider that the rheumatic diathesis furnishes the reason for their unusual susceptibility. It only remains to mention the fact that a disposition to gout seems to favor the development of muscular rheumatism. In gouty families, therefore, it has been observed to be common.