The concept of collagen diseases in medicine.

The topic of this address was suggested by the Program Committee and I have accepted it with some apprehension. While my co-workers and I (1) are responsible for the term and a somewhat vague concept behind it, I do not feel that we have contributed very much to its further elucidation. Yet great advances have been made by others in the nearly twenty years since the term was.. proposed as an heuristic idea. which, if further explored, might have som~ .importance for the comprehension of the nature and pathogenesis of certain puzzling maladies. I should like to present to you the evolution of observations and thoughts which have led to theooncept and the sequence of investigations which mark the progress .of our knowledge within the past t decades. The term collagen is generally used synonymously with that of diseases of the connective tissue. I shall later in my presentation touch upon the reason we preferred the former designation, but I might say here that I do not object to the latter term if one is aware of the assumptions upon which both terms are predicated. A systemic implication of the fibrous tissue was postulated in 1838 by Bouillaud (2) to account for the simultaneous involvement of the joints and of the heart in acute rheumatic fever; but this induction, important as it was for diagnosis and prognosis in clinical medicine, did not stimulate investigations or' the pathogenesis of rheumatic fever. One can understand this failure if one considers the state of information about the connective tissue one hundred and twenty years ago. Nearly up until that date it had been regarded as a primordial tissue endowed with almost miraculous potencies of proliferation and unlimited differentiation. But a reaction had taken place in Bouillaud's time, and it had become an insignificant component of the animal