The hypodermic needle has no inventor; man introduces things percutaneously as experiment, as acupuncture, or as tattoo, then finds the result pleasing. He inoculated himself with smallpox in the 17th century or earlier, or he rubbed mercury into his skin for the great pox. Development of the hollow needle refined the process which continues unabated. Never content with having been born "to this isthmus in a middle state," man seeks to improve upon nature.
From the viewpoint of public health he has succeeded. Without having improved his genetic quality during the last hundred years, man has improved his prospect of escape from many infectious humours. Irony is found in the phenomenon that paralytic poliomyelitis appears when good hygiene eliminates immunity naturally derived from early spread of enterovirus through a population. Then man must immunize because he sidetracked nature. No matter, the good health balance favors the man-made hygiene.
Increased numbers