He held it up carefully and poured three or four cubic centimetres of it into the first tube so that it ran carefully down the side in a manner such as to form a sharp line of contact between the heavier culture with the acid and the lighter nitrite solution.
“You see,” he said, “the reaction is very clear cut if you do it this way. The ordinary method in the laboratory and the text-books is crude and uncertain.”
“What is it?” asked Pitts eagerly, leaning forward with unwonted strength and noting the pink colour that appeared at the junction of the two liquids, contrasting sharply with the portions above and below.
“The ring or contact test for indol,” Kennedy replied, with evident satisfaction. “When the acid and the nitrites are mixed the colour reaction is unsatisfactory. The natural yellow tint masks that pink tint, or sometimes causes it to disappear, if the tube is shaken. But this is simple, clear, delicate—unescapable. There was indol in that food of yours, Mr. Pitts.”
“Indol?” repeated Pitts.
“Is,” explained Kennedy, “a chemical compound—one of the toxins secreted by intestinal bacteria and responsible for many of the symptoms of senility. It used to be thought that large doses of indol might be consumed with little or no effect on normal man, but now we know that headache, insomnia, confusion, irritability, decreased activity of the cells, and intoxication are possible from it. Comparatively small doses over a long time produce changes in organs that lead to serious results.
“It is,” went on Kennedy, as the full horror of the thing sank into our minds, “the indol-and phenol-producing bacteria which are the undesirable citizens of the body, while the lactic-acid producing germs check the production of indol and phenol. In my tests here to-day, I injected four one-hundredths of a grain of indol into a guinea-pig. The animal had sclerosis or hardening of the aorta. The liver, kidneys, and supra-renals were affected, and there was a hardening of the brain. In short, there were all the symptoms of old age.”
We sat aghast. Indol! What black magic was this? Who put it in the food?
“It is present,” continued Craig, “in much larger quantities than all the Metchnikoff germs could neutralise. What the chef was ordered to put into the food to benefit you, Mr. Pitts, was rendered valueless, and a deadly poison was added by what another—”
Minna Pitts had been clutching for support at the arms of her chair as Kennedy proceeded. She now threw herself at the feet of Emery Pitts.