In that form of intensive agriculture to which is given the designation horticulture, there may be recognized several more or less distinct divisions, as fruit growing, market gardening, truck farming and floriculture. Each has its own special problems, based upon conditions of culture and market. While, as in all classifications, there is more or less overlapping, the tendency is for them to become more and more distinct. The market gardener is the producer of vegetables for a local market, while the truck farmer produces similar products for a larger or wider distribution. The former grows a great variety of products, disposing of them in relatively small quantity, not infrequently directly to the consumer. The latter raises a few highly specialized crops which he sells in gross, usually through a commission merchant. Truck farming has developed since 1860, in consequence of the growth of large cities, which require enormous supplies of vegetables of fairly uniform quality, and on account of the continuous demand for fresh vegetables as nearly as possible throughout the year. Watermelons and sweet potatoes can be raised in the southern states and laid down in New York City or Boston more cheaply than they can be raised in the suburbs of these cities, and, what is equally important, they will be of superior quality. The extension of railway facilities, the introduction of refrigerator cars and the building of cold storage plants has made it possible to grow in one climate products to be consumed in another. Cold storage has enabled the fruit growers of California to supply the eastern markets with peaches and other fresh fruit. Chicago, to give only one example, begins to receive strawberries, cabbages and tomatoes from the shores of the Gulf of Mexico early in the year and continues to receive these products, until finally they are being shipped late in the summer from the shores of Lake Superior. It is estimated that the change of locality from which these products come, travels northward at the rate of from 13 to 15 miles a day. IMPORTANT FACTORS IN INTENSIVE FARMING In the neighborhood of large cities, notably in the environs of Paris, market gardeners often produce their vegetables in made soil. The local character of the soil under such conditions is a matter of comparative indifference, since a board floor would answer every requirement as a resting place for the artificial soil. The large expense in preparing and constantly renewing the seed bed is only economically possible, however, where proximity to a large city out-weighs all other considerations.