He paused, and they saw the flicker of a smile in his weary eyes.
"The whole scheme is under van Heerden's hand. At the word 'Go' thousands of his agents begin their work of destruction—but the word must come from him. He has so centralized his scheme that if he died suddenly without that word being uttered, the work of years would come to naught. I guess he is suspicious of everybody, including his new Government. For the best part of a year he has been arranging and planning. With the assistance of a girl, a compatriot of his, he has reduced all things to order. In every country is a principal agent who possesses a copy of a simple code. At the proper moment van Heerden would cable a word which meant 'Get busy' or 'Hold off until you hear from me,' or 'Abandon scheme for this year and collect cultures.' I happen to be word-perfect in the meanings of the code words because van Heerden has so often drummed them into me."
"What are the code words?"
"I'm coming to that," nodded Milsom. "Van Heerden is the type of scientist that never trusts his memory. You find that kind in all the school—they usually spend their time making the most complete and detailed notes, and their studies are packed with memoranda. Yet he had a wonderful memory for the commonplace things—for example, in the plain English of his three messages he was word perfect. He could tell you off-hand the names and addresses of all his agents. But when it came to scientific data his mind was a blank until he consulted his authorities. It seemed that once he made a note his mind was incapable of retaining the information he had committed to paper. That, as I say, is a phenomenon which is not infrequently met with amongst men of science."
"And he had committed the code to paper?" asked Kitson.
"I am coming to that. After the fire at the Paddington works, van Heerden said the time had come to make a get away. He was going to the Continent, I was to sail for Canada. 'Before you go,' he said, 'I will give you
