answer questions concerning the finer structure of the cell elements, we are bound to resort to indirect methods. The latter have, in a relatively short time, opened up a vast field, and discovered views of the widest interest in regard to every kind of cellular process. It is the duty of the future to follow up with exact methods all the observations that have been made, and to replace with known quantities the many unknowns with which our present-day methods have still to reckon.
If we sum up all the phenomena observed, we get the following picture: By introducing substances which are out of harmony with the species, and more particularly with the plasma, we bring into the organism bodies which are, in their whole structure, absolutely disharmonious with the cells of the body. No alteration has as yet taken place. In order that these substances may be utilized by the cells of the body, the products that are suitable for the organism must be so far decomposed as to entirely lose their specific character. This decomposition is effected by ferments, and is certainly initiated very quickly, for the disharmony with the blood or plasma and the body may extend also to the cells, and have an injurious effect on them. During the decomposition of these substances products arise at first which are, in part at least, definitely disharmonious with the
