_Bacillinum_--since it must be distinguished from Koch's _Tuberculin_--is a maceration of a typical tuberculous lung.[G] Koch's lymph is an extract in glycerine of dead tuberculous bacilli. The former is compound natural infection; the latter is a product of laboratory experiment. In the one, various bacteriological species are associated which give, clinically, an appearance of cachexia and of hectic fever; from the other we may sometimes observe vascular, cardiac, renal changes having no connection with the clinical "syndrome" of pulmonary tuberculosis. To place these products together in the same pathogenesy gives an absolutely wrong sense, and the fact that both contain Koch's bacillus gives no excuse for confounding them. In my opinion there are, from a homoeopathic point of view, distinct differences between _Bacillinum_ and the Koch's lymph. [G] Dr. J. Compton Burnett, in his book, "New Cure for Consumption," p. 129, makes this remark: "The best way to get some really good _Bacillinum_ is to take a portion of the lung of an individual who has died of genuine bacillary tuberculosis pulmonum, choosing a good-sized portion from the parietes of the cavity and its circumjacent tissue, as herein will be found everything pertaining to the tuberculous process--bacilla, _débris_, ptomaines and tubercles in all its stages (such was practically the origin of the matrix of my _Bacillinum_) and preparing by trituration in spirit. In this way nothing is lost." Experimentally Koch's bacillus, like many other microbes, does not reproduce a clinical symptom-group; and we homoeopaths must have an assemblage of clearly-defined symptoms before prescribing a poison on homoeopathic principles. Such is unfortunately the case with many other microbes in pure culture. The experimental diphtheria does not resemble clinical diphtheria. The pneumococcus, pathogenetic of pneumonia, is met with in many other diseases, such as pleurisy, salpingitis, meningitis, etc. Koch's bacillus, too, sometimes remarkably mild in its effects, and seeming to meet with no reaction in the system, evolves aside as in the verrucous tuberculosis; while at other times nothing is able to arrest the action of this terrible microbe, and the world still waits in vain for the man who shall find the means of combatting it. The toxins of tuberculosis are far from reproducing clinical tuberculosis; yet even here we find a curious aspect sometimes assumed by certain poisons drawn from the pure cultivation of microbes. We cannot produce with _Tuberculin_ symptoms analogous to those of real tuberculosis--as it is possible, for instance, to produce tetanus with the toxine alone, _Tetanin_.