"On guard at the gateway".

TO the general public the work of the Port Health Service is little known with the result that it gets very little publicity except on those rare occasions when a large passenger liner is held up with a case of suspected smallpox on board. Port health authorities whether they are concerned with a seaport or airport have one major function and that is to protect the country of which they are the gateway from disease introduced from outside sources. The history of the port health services of the world has been one of evolution of theories and accumulation of knowledge. It has involved the epidemiology and control of communicable diseases which have in past centuries threatened the very existence of mankind. When disease was thought to originate, only in an obviously sick person, preventing its spread seemed a comparatively simple procedure; isolate the sick person and there should be no further spread of the disease. This was so, even in the days when travel between countries was slow and along well established trade routes overland or by sea. Even the threat of the death penalty, which was there to compel sick persons to remain apart from their fellows, was ineffective. During the many centuries when epidemic disease was thought to be a visitation from the Almighty little could be done to prevent its spread save by prayer, sacrifice or resort to witchcraft. As soon, however, as more rational views prevailed, and when it was realized that persons and goods coming from an infected area to a healthy one could introduce an epidemic, efforts were made to mount guards at the gateways to towns and continents to prevent these disastrous calamities. These guards, in the form of rules and regulations set up many centuries ago, were the forerunners of the port health services of today. The course, though not the actual mechanism of spread of these importations of disease, was soon recog-nised-e.g., the actual spot near Weymouth where the man landed, who! imported the Black Death into England in 1348, is known and his route from there has been traced. Through the research of Spanish historians we also know the name of the negro who first brought smallpox to the Indians in Mexico, in 1520 and paved the way for the 3j million deaths from smallpox which followed. The origin of the well known and disastrous epidemic of plague, which struck …