"This," he explained as he set down the vial, "is a substance which gives a colorless solution with water, but when mixed with albumins, peptones, or amino-acids becomes violet on boiling. Tube number three must remain colorless. Number two may be violet. Number one may approximate number two or be more deeply colored. If one and two are about the same I call my test negative. But if one is more deeply colored than two, then it is positive. The other tube is the control."
Impatiently we waited as the three tubes simmered over the heat. What would they show? Seabury's eyes were glued on them, his hand trembling in the presence of some unknown danger.
Slowly the liquid in the second tube turned to violet. But more rapidly and more deeply appeared the violet in number one. The test was positive.
"What is it?" gasped Seabury hoarsely, leaning over close.
"This," exclaimed Kennedy, "is the famous Abderhalden test—serum-diagnosis—discovered by Professor Emile Abderhalden of Halle. It rests on the fact that when a foreign substance comes into the blood, the blood reacts, with the formation of a protective ferment produced as a result of physiologic and pathologic conditions.
"For instance," he went on, "a certain albumin always produces a certain ferment. Presence in the blood stream of blood-foreign substances calls forth a ferment that will digest them and split them into molecules. The forces of nature form and mobilize directly in the blood serum.
"Let me get this clearly. Albumin cannot pass through the pores of an animal membrane, since the individual molecules are too large. If, however, the albumin is broken up by a ferment-action, then the molecules become small enough to pass through."
Seabury was listening like a man on whom a stunning blow was about to descend.
"Thus we can tell," proceeded Kennedy, "whether there is such a ferment in blood serum as would be produced by a certain condition, for when the ferment is there blood from the individual possessing it will digest a similar proteid in a dialyzing thimble kept at body temperature.
"Why," cried Kennedy, swept along by the wonder of the thing, "this test opens up a vista of alluring and extensive possibilities. The human organism actually diagnoses its own illnesses automatically. It is infinitely more exact, more rapid, and more certain than all that human art can attain. Each organ contains special ferments in its cells in the most subtle way attuned to the molecular condition of the particular cell substance and with complete indifference to other cells.