This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 edition. Excerpt: … infections are old enemies. Organisms strange to each other have no rules for fight. This is evidenced by the high mortality which results from the introduction of infections into countries in which they are not indigenous, so that natural selection has had no opportunity to protect the organism by a long series of selective struggles. When measles was first introduced into Samoa by Europeans, it wrought a cruel havoc among the natives. When la grippe was first imported into Russia, it ran a severe course. In like manner, many of the terrible epidemics of plague in ancient history may have been due to the appearance of some new germ or the spasmodic rehabilitation of an old one. Distribution of Chemical Ceptors The same relation which exists between contact ceptors and their distribution in those parts of the organism, where harm-producing agents would have been encountered throughout its evolution, exists between chemical ceptors and the parts of the body most commonly exposed to the local invasion of infectious agents. Many of these areas, such as the skin surface and the superficial organs, are identical with the pain areas, but many other parts of the body, which are totally devoid of the contact ceptors, are abundantly provided with chemical ceptors for the apprehension of their own specific menaces. The surfaces of the face, the neck and scalp, the extremities, the eyes, the nose, the throat and the lungs, which have constantly been exposed to pyogenic infections, are, as one would expect, well equipped with protective mechanisms. The lungs, which make no response to perforation by an external agent, respond actively to the invasion of pneumococci, since these are ancient enemies. The peritoneum, which throughout phylogeny has…