Some one has said that if one wishes to learn bow much is known of the etiology of a certain disease it is only necessary to look at the chapter on its treatment; if the list of remedies is large and diversified, it is an evidence that but little is known of the cause of the disease in question. In spite of the great advance made in dermatology, psoriasis still remains a disease that baffles our therapeutic skill, mainly because we are uncertain as to its etiology. This introduction will serve as an excuse for presenting a paper on such a trite subject as psoriasis. While it is perhaps necessary to touch on the etiology of this disease, time will not permit of a detailed discussion, nor is it material, except in so far as it is necessary to explain why this treatment was instituted. The claims of those who