unexpected infusoria that are killed by quinine, and announces to the world in one breath a theory of the disease and a specific for its cure, without apparently suspecting, what is now known, that the presence of infusoria might be a coincidence or effect and not a cause.
To all this it may be said that practically we do find out the true value of medicines and their objective action on the human body without systematically eliminating any of the six elements of error here pointed out. This is to be allowed; but the admission of the fact requires also an explanation of the way in which these errors are in practice actually eliminated, although unintentionally and unsystematically, and I may say also, most unscientifically.
It is by an immense number of experiments or trials on a large variety of cases, at different times, by different observers, and under varying conditions, that medical science has been able, after centuries of doubt and struggle, to arrive at some few real scientific facts in regard to the action of medicines. If these six elements of error had, from the first, been everywhere recognized and comprehended and systematically guarded against, the process of finding the truth in this department might have been abridged by hundreds of years. The method by which, in practice, physicians learn the action of any new remedy, is to give it to a number of cases, and then to watch and report the results; another physician repeats the experiments on a different set of cases; he also notes the results: and this process goes on perhaps for years, until in lapse of time the profession, without being able to give precise and convincing reasons for their faith, slowly and instinctively settles down to the persuasion that the effects claimed for the remedy are genuine, and act accordingly.
In many instances they are right in this conclusion; but how awkwardly and in what a roundabout way, and through what useless and wearying toil, have they, in doubt and distrust and suspicion, finally reached that goal! All the trials with the remedy, from beginning to end, have been impaired in scientific value by some one or all of the six elements of error; but through the immensity and variety of the experiments, extending through a long period, these errors have been unconsciously and unwittingly eliminated, so that only the solid fact is left. This unconscious elimination or rather leaving behind of errors, after the analogy of the formation of the universe according to the nebular hypothesis, takes place in this manner: In the first hundred cases treated there will be perhaps one of two, or more, who have no faith in and no expectation from it, good or bad; these few obtain the real objective effects of the remedy, while all the others deceive, more or less, themselves and their physician. In subsequent experiments by other observers, some of whom perhaps are less hopeful than the original investigator, the same unconscious and irregular elimination takes place, until the objective power of the remedy may for all practical needs be regarded as established. Such is the history and philosophy of medical experi-
