When an experiment or a scientific application requires a purified compound, the chemist goes to work. When a substance is to be altered so that it takes on a different form, the chemist takes over. He develops better fuels for automobiles and space craft, better fibers for shirts and parachutes, better plastics for kitchens and submarines. Biology Biology deals with the structure and behavior of plants and animals: the botanist studies plants, the zoologist studies animals, and they both can use radioactivity widely in their research. Radiation changes the pattern of plant behavior, and many botanists are vitally interested in the effect of various types of radiation on seeds and plant growth. Radiation can produce mutations, or basic changes, in growing things; thus, by selective breeding of desirable changes, it is possible to improve crops. Progress here is slow. Many millions of possibilities exist in the relations among the variety of plants, type and intensity of radiation, random chance, and other growing conditions, but already several new plant breeds have emerged, and other crops are bound to follow. In addition to altering plants directly by radiation, the botanist can improve plants indirectly by using radiation: he can add radioactivity to fertilizer and evaluate the efficiency of its uptake by the plant to determine the most effective fertilizer for a particular soil or crop. The many, and sometimes seemingly strange, effects of radioactivity on plants and growing conditions provide a wide and fascinating field for the botanist. As most people know, radiation also affects animal tissue. The zoologist wants to know how and why this is true and how varying conditions alter animal reactions to radiation. The research of the animal physiologist is basic to later medical applications of radiation to human beings. The veterinary scientist has the grave responsibility of testing radioisotopes, radiation drugs, chemicals, surgical procedures, and various combinations of these in animals to determine which can be used to diagnose or cure disease in man. He passes his findings on to the physician for further research only after he has made every possible test and evaluation. Sometimes he works with chemists, nutritionists, bacteriologists, and other scientists. What happens to animals could happen to human beings, and that is why physiologists watch carefully the animals that eat radioactive foods and study the offspring of animals that have been exposed to radioactivity. [Illustration: Animal studies using radioactive materials give important information concerning physiology, both animal and human.] Geology A main interest of the geologist is the history of the earth and its ever-changing life, especially as revealed in fossil formations and deposits under the soil.