Note 18 — Chapter V · HEALING A NATION
Reading edition
The cause of the pneumonic plague is so little known that it may be interesting to mention it here. The disease, it is said, is carried by marmots. It had not broken out since the fourteenth century, because Manchu hunters had for generations been taught not to kill marmots for this very reason. But in late years, with the great demand for furs, new hunters who knew nothing of this, killed the diseased marmots and so caused an epidemic.