At the outset, while it may seem trite, it may be well to define the sense in which the term etiology is used as well as to indicate what is meant by the term rheumatism. We here employ the term cause in the same sense as we do in typhoid fever, pneumonia, pulmonary tuberculosis, etc., in which we recognize that aside from the infective agent there must be what some have called the soil, susceptibility to infection varying from extreme susceptibility on the one hand to complete immunity on the other; and that the latter may for certain animals and diseases be variable in degree and also either hereditary or acquired.
In order to limit discussion the term rheumatism will be confined to those cases of non-suppurative arthritis occurring especially in children, but which also occur in the adult. This is the view of Poynton and Paine1 They say: "All suppurative arthritis must, we think,