The materia medica of _Tuberculin_ takes its rise in the complex result of the use of Koch's lymph, in experiments upon animals, and in certain symptoms observed by those who have experimented upon themselves with different products of tuberculous nature. I shall therefore indicate the published sources, and I specially desire to place before the Homoeopathic Congress of London the tuberculous virus under certain aspects which are perhaps new; and if my conclusions seem somewhat paradoxical I am content to accept, with a good grace, the criticisms of my colleagues. Fourteen years anterior to the researches of Koch, Hering, Swan and Biegler availed themselves, as a homoeopathic remedy, of the maceration of tuberculous lungs, and of the sputa of tuberculous subjects. Dr. J. Compton Burnett in his book, "A Cure for Consumption," several years before Koch's experiments, noticed symptoms resulting from taking the preparation which he calls _Bacillinum_. Drs. de Keghel[C] and J. H. Clarke[D] instituted an inquiry into the symptoms produced by the employment of Koch's lymph in the case of tuberculous and non-tuberculous patients. [C] _L' Union Homéopathique_, vol. v, No. 3. [D] _Homoeopathic World_, vol. xxvi, No. 304. Dr. Mersch[E] published a pathogenesy, based to a large extent upon that of Dr. de Keghel; it is an excellent work. [E] "On Tuberculin," an extract from the _Journal Belge d' homéopathie_, 1895. Dr. d'Abzen,[F] of Lisbon, sent to the Tuberculosis Congress of 1895, at Coimbra, a study of the works of Koch and Pasteur, and an enumeration of the treatises published by homoeopathists. [F] _Pathogenese, sua importancia._ We must notice also an English translation of Dr. Mersch's pathogenesy, by Dr. Arnulphy, of Chicago, in which special attention is paid to the symptoms observed in healthy and non-tuberculous persons, with some original remarks about _Tuberculin_. It is published in the _Clinique_ for this year (February, 1896). Nor must we overlook a series of writers who have published isolated observations of the cases of persons cured with _Tuberculin_. Such are Drs. Lambreghts, Joussett, Zoppritz, Horace Holmes, Richardson, Young, Clarke, Pinart, Youman, U. H. Merson, Snow, Lamb, Clarke, Ebersole, W. James, Kunkel, A. Zoppritz, Steinhauf, Van den Berghe, &c. Finally, for my own part, in my articles in _L'Art Médical_, published three years ago, and in the _Hahnemannian Monthly_ (July, 1894), I have insisted on homoeopathic action of the viruses of tuberculosis. In certain of the pathogenesies of _Tuberculin_ we find thrown pell-mell together symptoms appertaining to Koch's lymph, as well as others which belong to the product baptized by several names, such as _Bacillinum_ and _Tuberculin_, in the recommendation of which Hering and Swan, and Dr. J. Compton Burnett, in England, have made themselves conspicuous.