Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/131

 retarded by the addition of optically active a-amino-acids. It is a matter of indifference what kind of a-amino-acid is used, provided only it belongs to the units of the protein. We demonstrate the decomposition of a specifically constructed substrate, while the methods in question are concerned only with the influence of the products that are split off.

Of course, the mere fact, that it has been found possible to found a sero-diagnosis of pregnancy on the principles described above, would not give us the right to speak of a sero-diagnosis of the functions of organs. Further research, based on these principles as well as on the methods described, has, however, given us results which entitle us fairly to presume, that a new road has already been found for the development of our knowledge of the structure and metabolism of cells, under normal and pathological conditions.

As, meanwhile, our knowledge of the physical and chemical properties of the complicated constituents of the cell, and the products of its metabolism, is still very scanty, while in addition the disharmonious components of the plasma only appear in minute quantities, we are not in a position to seek them out by direct means. We have, therefore, to hit upon indirect means, and to find out whether a particular blood serum has ferments at its disposal, which are