isolated from cultivations of the Bacillus anthracis albumoses which were found by Hankin to produce immunity from the disease when injected into the body. Possibly under the influence of Hankin, certainly later in the year, the important researches of Fraenkel and Brieger on the toxalbumins of diphtheria, typhoid fever, cholera, tetanus, etc., were published. Thus, just as in the case of many remedies used for centuries in the shape of powders, extracts, decoctions, infusions, tinctures, etc., active principles have ultimately been discovered by chemists, it was now found that out of the material used for the last ten years by Pasteur and his school, it was possible to isolate some active products of definite composition, to which the lymphs or "vaccins" owe their prophylactic and curative properties. Such was the state of science when, in the course of last year, it was announced that Koch had found the means of curing phthisis by inoculation. All minds were to a certain extent prepared for such an announcement; yet the fact that one of the greatest scourges affecting human kind had at last come within the pale of treatment has created immense sensation. The little that is known of the treatment and of its effects seems to point clearly to the fact that Koch is using some of the chemical products which have just been discussed, and therefore there is good reason to expect that a certain amount of success will attend the method. The results of previous experimenters show, however, that it would be wrong to hope too much from a system which has always been attended with a certain proportion of failures.
I have carefully avoided in this exposé to enter into many details, some of which are of great importance, in order that you should be able to follow the main line of observations and thoughts which have led to the recent discovery. I will therefore not attempt to discuss on what basis vaccination, essentially prophylactic in principle, may become a curative method when the modified virus answers certain requirements. There is a very distinct connection between these two methods of treatment.[1] It may, however, be interesting to consider for a moment the methods which the knowledge of pathogenic organisms has introduced in medicine.
These methods can be subdivided into three classes: (1) The preventive, (2) the protective, (3) the curative. They have all something in common, and yet they all differ, as will be seen in the following brief enumeration:
1. The preventive method consists in destroying or attenuating
- ↑ For explanation as to the mode of action of the products used in vaccination, see Lauder Brunton's lectures on Chemical Structure and Physiological Action, especially Lecture II (British Medical Journal, vol. i, 1889, p. 1389).
