Koch states that he can not at the present make any statement about the origin and preparation of the remedy, as his labors are not yet completed.

We may assume that it is very probably a substance that corresponds in a way to the lymph used for vaccination. As vaccine lymph represents variolous poison greatly reduced in strength, as the remedy for hydrophobia is composed of a substance which is weakened hydrophobic poison, so Koch probably obtains his remedy for tuberculosis by artificially reducing the tuberculous poison by means of various processes.

A number of years ago it has been tried with syphilis in a similar way to obtain a substance that would not only cure syphilis but would also guard against infection from it. At that time however the experiment was not successful.

From several intimations I am inclined to believe that Koch was successful in finding a way in which a substance may be produced for contagious diseases, a substance that cures these diseases and also protects from infection. It is not impossible, since Jenner found the vaccine virus, Pasteur the hydrophobic lymph and now Koch the tubercle lymph.To be sure there is this difference for the present between the substances named, that the vaccine virus only protects healthy person from infection by small pox but it does not cure those sick, while the hydrophobic lymph and tubercle lymph cure the afflicted. However Koch seems to believe that his tubercle lymph has a certain power of producing immunity.

According to Koch, his remedy, consisting of a brownish liquid, is easily perishable as soon as it is diluted with water; he recommends the preparation of the dilution of the remedy with a 5 per cent. phenol solution. Phenol is equivalent to carbolic acid. The dilution of the remedy for use must be considerable, as only small quantities of the same are used.

Koch tells us that his remedy does not act through the stomach, that is taken in through the mouth. On one hand it may be that this is due to the extremely small quantities necessary for an effect, on the other hand and principally all the substances probably act only when they are directly applied and brought in contact with the circulation of the blood.

For a long time small syringes with fine needle points were used to inject strong acting drugs under the skin. This is done in a measure to have a guarantee of a sure effect which is not had by giving through the mouth. For instance, it is known that emetics given through the mouth often remain without results; if however the emetic apomorphine is injected anywhere under the skin, vomiting surely follows within a very short time. It is well known that morphine is injected under the skin in preference to taking it through the mouth as its action as a pain killer is much prompter.

Koch's liquid can also be injected under the skin with the aid of a so-called Pravaz syringe. Koch uses a somewhat differently formed syringe. The result remains the same, no matter what kind of syringe is used.

At the same time it makes but little difference, on what part of the body the injection is made, as the fluid injected under the skin is distributed at once over the entire system. Koch chose the skin of the back between the shoulderblades and the loins because here the injection could be made without causing pain or inflammation.

The production of the liquid must be attended with great difficulties as Koch plainly remarks that his stock at present is very limited and he can only furnish larger quantities at the end of several weeks. The price of a small bottle to be 25–30 Marks about 6–8 Dollars.The human being is much more sensitive to Koch's remedy than the guinea pig, which is commonly used for experiments of this kind. It seems that no experiments have as yet been made with other animals.

Koch has tried the remedy on himself and has passed through all the symptoms of a poisoning. He certainly injected into his arm a considerable quantity of the liquid; twenty-five times as much as he injected in his patients.

But here also there is a difference. In sick people much smaller quantities act than in the healthy. One cubic centimeter of the liquid has hardly any effect on a healthy person, but quite a marked one on those afflicted with tuberculosis.

In the case of the latter one cubic centimeter produces about the same symptoms as twenty-five times the quantity would in a healthy person. The same must also be considered as symptoms of poisoning; but they are only of short duration and are accompanied with magnificent success.

Of all diseases based on tuberculosis only ringworm or lupus is perceivable by the eye, as it is a disease of the skin, all other tuberculous diseases take their course in the internal parts of the body, and therefore are not perceptible to the eye. The symptoms that follow an injection of Koch's liquid can be best observed in the case of lupus.Koch therefore selected for his first illustration patients afflicted with lupus that is ringworm. Even a few hours after the injection the first perceptible changes begin to show in the diseased parts. These begin to swell and redden; in other words an inflammation is caused, through which the diseased tissue is obviously brought to mortification. Soon the inflammation stops. The gangrenous tissue changes into crusts or scabs which drop off in a short time and the patient is cured of his ringworm.

Koch places particular importance on the fact that the inflammation is restricted to the diseased parts only, and that it does not attack sound and healthy parts. Even the smallest otherwise invisible knots are made perceptible through the inflammation.

We have similar illustrations for this specific action of Koch's remedy for lupus (ringworm). So for instance a syphilitic ulcer on the thigh may be cured in a few days with iodide of potassium. In a similar manner a morbidly enlarged spleen may be reduced to the normal size by taking quinine.

The observation is very interesting indeed, as it may be shown whether a person is tuberculous in any organ or not by the injection of .01ccm. In case he is tuberculous the poisoning symptoms appear in a marked degree; if he is not, hardly any effect is noticeable.Although we have had excellent methods for a long time to detect pulmonary consumption, although Koch added the discovery of the tubercle bacilli, it occasionally happens that the disease can not be recognized in its beginning stages, because its progress is too slight. Now the reaction following an injection is to be the deciding medium. Also with other tuberculous affections physicians will welcome this diagnostic auxiliary, for in the beginning of the same it often happens that no certain diagnosis could be made and valuable time was lost.

We must call particular attention to the further statements of Koch, that through his remedy the tubercle bacilli are not killed. With this it is admitted that the remedy will not be able to effect cures, without any more ado, yes, even the tubercle bacilli may continue to infect parts of the body even in spite of the action of the remedy.

Therefore the application of Koch's remedy only, is not sufficient to effect a cure. Provision must be made to remove the gangrenous tissue from the body as rapidly as possible, because it contains the still living tubercle bacilli. As a rule surgical aid is necessary to remove the mortified tissue. Where this is impossible Koch advises the continued application of the remedy to protect the endangered living tissue from the re-immigration of the tubercle bacilli. Koch thereby believes that he can protect the tissue, perhaps in the manner as vaccination protects from small pox.

The rapid increase in the quantity of the remedy applied in the course of time is something that has no parallel. Koch gives an explanation, but leaves it to the future to be confirmed. We have no previous instance in case that his explanation should prove correct. Reasoning from analogous application of our remedy, we are led to assume that smaller quantities of the substance would suffice to cause mortification of the remaining tuberculous tissue. Koch on the other hand uses larger and larger doses to reach a result. He admits inurement to the remedy within certain limits only.

Koch has made a difference between pulmonary consumptives and those suffering from tuberculosis of the bones and joints, etc. He was able to inject larger quantities in the latter than the former, for the quantity injected in the case of pulmonary consumptives was .001ccm.; in other tuberculous cases .01ccm.

Koch selected pulmonary consumptives for his experiments, whose sputum contained tubercle bacilli, so as to make no error in the diagnosis, and to ascertain by killing the bacilli contained in the sputum, whether the diseased tend toward restoration. As the remedy does not kill the bacilli, so a diminution of the bacilli can only be obtained in that manner, that the tissue of the lungs undergoes certain changes, which cause its properties to be such, that the bacilli are no longer able to exist or propagate in them. Then a so-called immunity results which we know of in other similar diseases. We know that anyone who has had the measles or scarlet fever rarely is again attacked by the same, as a rule he is permanently proof against them.

In the same way as vaccination protects from small pox, an injection of Koch's remedy acts against pulmonary consumption. Koch makes a cautious statement:

Koch reaches this result, that beginning phthisis can with certainty be cured with his remedy. On the other hand, advanced consumptives, in whose lungs large cavities already exist, may possibly be improved but can not be cured. However he provokes the idea, that perhaps his method of treatment together with a surgical operation, that removes all gangrenous matter from the lungs, may yet have beneficial results in the end. The idea is not entirely new to treat lung diseases with the aid of surgery; unfortunately the operations have heretofore been thought too risky. Perhaps we will now have a new branch in operative technic, surgery of the lungs. Koch advises to conduct this lung surgery after the manner of operating empyema. This is an operation performed in the case of suppurative pleurisy to remove the pus from the pleural cavity. This operation has been successfully carried out for a long time.

Koch makes it of especial importance, that while treating consumption with the new remedy, the general attendance and nursing is not to be neglected. Koch also calls attention to what has been said before, that the general hygienic factors, good hospital treatment, mountain climate, etc., will never be dispensed with, on the contrary will be indispensible to the furtherance of cure.

In conclusion Koch again remarks that brilliant results are only promised in the early stages of pulmonary consumption (phthisis). Physician and patient must move all levers as to the existence or non-existence of tuberculous diseases.

Then those daily pictures of extreme wretchedness from consumption will be a thing of the past. Then the danger of contagion will be lessened resulting from the decrease of the number of tuberculous persons and of the tubercle-bacilli, and perhaps it will soon be possible to name the day on which with the last tubercle-bacillus the ravaging pest, tuberculosis, will be extirpated.