"The Foreign Medical-Cavalier," said Beale, "was Doctor van Heerden. The date was 1915, when the doctor was taking his summer holiday, and I have had no difficulty in tracing him. I sent one of my men to Vigo to interview Doctor Romanos, who remembers the circumstances perfectly. He himself had thought it wisest to destroy the germ after carefully noting their characteristics, and he expressed the anxious hope that his whilom friend, van Heerden, had done the same. Van Heerden, of course, did nothing of the sort. He has been assiduously cultivating the germs in his laboratory. So far as I can ascertain from Professor Heyler, an old German who was in van Heerden's service and who seems a fairly honest man, the doctor nearly lost the culture, and it was only by sending out small quantities to various seedy scientists and getting them to experiment in the cultivation of the germ under various conditions that he found the medium in which they best flourish. It is, I believe, fermented rye-flour, but I am not quite sure."
"To what purpose do you suggest van Heerden will put his cultivations?" asked the commissioner.
"I am coming to that. In the course of my inquiries and searchings I found that he was collecting very accurate data concerning the great wheatfields of the world. From the particulars he was preparing I formed the idea that he intended, and intends, sending an army of agents all over the world who, at a given signal, will release the germs in the growing wheat."
"But surely a few germs sprinkled on a great wheatfield such as you find in America would do no more than local damage?"
"Mr. O'Donnel," he said soberly, "if I broke a tube of that stuff in the corner of a ten-thousand-acre field the whole field would be rotten in twenty-four hours! It spreads from stalk to stalk with a rapidity that is amazing. One germ multiplies itself in a living cornfield a billion times in twelve hours. It would not only be possible, but certain that twenty of van Heerden's agents in America could destroy the harvests of the United States in a week."
"But why should he do this--he is a German, you say--and Germans do not engage in frightfulness unless they see a dividend at the end of it."