AN INTRODUCTION TO THE STUDY OF PNEUMONIC FEVER.

FIFTH PAPER.—GEOGRAPHY.

Medical geography is, equally with historical pathology, one of the most fruitful means of eti- ological research. It enables us to become acquainted with the different regions of the globe in which certain diseases prevail, and thus allows upon the grandest scale the study of cosmic, tel- lurial and even anthropological conditions that may favor or hinder their development. Pneumonic fever prevails in every part of the world, but, as is the case with all other maladies, it is more common in some localities than in others. It is more prevalent in temperate than in either frigid or torrid regions. Beginning at the poles, its frequency increases in a gradual manner until the maximum is attained at a certain latitude in either temperate zone, and from these points it diminishes as we approach the equator, so that in some tropical countries the malady is somewhat of a nosological