The bureau of animal industry investigates the causes, prevention, and treatment of diseases of domestic animals, and has done much to eradicate them.  It studies methods of dairying and dairy manufacturing, of breeding and feeding livestock, of producing wool and other animal fibers, of poultry raising.  It cooperates with the States Relations Service and the state agricultural colleges in educational work, conducting livestock demonstration work and advising with regard to the establishment and management of creameries and cheese factories.  It promotes the organization of pig clubs to stimulate interest in swine production.

The bureau of plant industry investigates the causes, prevention, and treatment of plant diseases, including those of fruit, shade, and forest trees.  It has introduced over 43,000 varieties of foreign seeds and plants, from which many new industries have grown up amounting in value to many millions of dollars each year.  Its explorers have brought new varieties of cereals from Russia and Siberia; alfalfas from Siberia; date palms from North Africa, Arabia, and Persia; the pistachio nut from Greece and Sicily; vanilla and peaches from Mexico; barleys and hops from Europe; rices and matting rushes from Japan; forage grasses from India; tropical fruits from South America.  It experiments in the breeding of hardy and disease-resisting grains, fruits, and vegetables, studies soil fertility, investigates the medicinal qualities of plants, tests seeds, and improves agricultural implements.  Its experiments are conducted in experimental gardens in Washington, D.C., at Arlington, Va., and at the experiment stations distributed widely over the United States.

This bureau does much educational work, instructing farmers how to control plant diseases and how to organize for cooperation in the breeding of disease-resisting plants, and conducting demonstrations on reclaimed lands in arid regions.  During 1916 it distributed, through members of Congress, 356,000 tulip and narcissus bulbs, 96,000 strawberry plants of 15 varieties, 14,000 packages of lawn grass seed, and more than 16,000,000 packages of vegetable and flower seeds.

The bureau of chemistry studies the influence of environment on crops and plants; investigates the quality of mill products, the methods of bread making, of tanning leather, and of paper making.  It tests the food values of all kinds of products, the keeping quality of poultry, eggs, and fish in the course of transportation, and the composition of drugs.  It is called upon by other departments of government to make chemical analysis of many articles.

The bureau of soils investigates the quality of soils and their adaptation to different kinds of crops, and the fertilizer sources of the country.

The bureau of entomology is concerned with the study of insects and their relation to agriculture, including those that are destructive to fruit, shade, and forest trees.  Its work includes the study and promotion of bee culture.  It has carried on a campaign for the eradication of such diseases as spotted fever, malaria, and typhoid which are carried by ticks, mosquitoes, flies, and other insects (see Chapter xx).