Europe of To-day 613 a railroad station, and have their supplies sent out every week, or oftener, from the nearest large town, perhaps a hun- dred miles away. Still more important to the study of transportation than this withdrawal of the manufacturing classes into towns is the specialization of manufactures by districts, — what has been called the territorial division of labor. The principle that one can accomplish most by concentrating his energies on the thing that he is best fitted to do, has in our time been applied to places as well as to persons. Massachusetts has districts whose people are almost wholly occupied with shoemaking, and others where they are equally engrossed in cotton spinning. Pittsburg and the surrounding country is, roughly speaking, a vast iron furnace, Dakota a wheat field, and so on. Applied science is by no means confined to the in- vention of machinery and the facilitating of travel and intercommunication! Science has revolutionized our ideas of animal and plant life and of the treatment of maladies. By means of the most delicately adjusted microscopes it has become possible to discover and study the minute plants known as bacteria, some of which are not over a hundred and fifty thousandth of an inch in diameter. The study of the life histories of these diminutive plants 500. The excites the wonder of those who make observations upon beneficent them. It is truly marvelous to know that these bacteria (From can accomplish, in their short lives of possibly a few hours Dr. William or days, feats which would baffle the cleverest of chem- 0sler -) ists if given years of a lifetime to work upon. They give to the farmer the good quality of his crops, to the dairyman superior butter and cheese ; they assist in large measure in freeing our rivers and lakes from harmful pollutions. Here it should be strongly emphasized that those bacteria which cause disease are only a few species, all others contributing to our welfare in countless ways.
