Plant and animal importation, improvement of breeds, and discoveries in genetics, soil chemistry, the use of fertilizers, and in controlling plant and animal diseases all helped the living things which form the basis of farming yield. Grain farmers not only had to have a wheat which yielded well but a wheat which resisted the attacks of nature. For example, Turkey Red wheat, introduced in 1873 by Mennonites from Russia, not only survived drought and yielded well but provided the genetic elements for newer breeds of wheat. The farmer not only wanted good-producing meat cattle, such as the Herefords, but had to control diseases and predators which killed the animals. Sick animals do not grow properly or, in the case of dairy animals, give much milk. Steady advances in disease control for both plants and animals brought fewer losses and greater productivity to farmers. The 19th century also brought scientific discoveries in both plant and animal nutrition. Fertilizer and soil chemistry made great advances through scientific experiments, at first by farmers and later by government servants. The first experiment station in the modern era began in Connecticut in 1875, and in 1887 the Congress established such stations in every state in conjunction with the agricultural Land Grant colleges. Scientists at many of the stations also made discoveries in animal nutrition. For example, as a result of animal feeding experiments E. V. McCollum discovered vitamins A and B at the experiment station in Wisconsin in 1915. None of these scientific advances left much residue in the form of artifacts for museums, but the reality of the changes should not be obscured by the lack of objects on exhibit. Even so, some of the related equipment survived. For example, the centrifuge used in the butterfat test, discovered in 1890 by Stephen M. Babcock, survived in several forms. Manure spreaders and tree sprayers, reflective of advances in biochemistry, also survived. But these only suggest the more important biological control activities for which these machines and tools served merely as agents in some way.