In Every Milk Bottle.

Professor S. M. Babcock was employed in the dairy department at the University of Wisconsin when he introduced his test in 1890. It is so well known among students of agriculture that it will need no detailed description here. With inexpensive equipment, it is possible to tell within a few minutes the butterfat content of a sample of milk. By adding a specified amount of sulfuric acid to a measured sample of milk and whirling it for a few minutes in a properly graduated container one may get the percentage of butterfat at a glance; and this percentage multiplied by the total weight of the milk will give the total amount of butterfat—in a can of milk, a cheese vat, or in the day's milk from a single cow.

Before the development of the test, a cow or a herd of cows was considered good or poor according to the amount of butter or cheese that was made from the year's milk. Few farmers, or others for that matter, understood that the amount of butter or cheese varied with the butterfat content of the milk. Neither the butter nor the cheese was an accurate measure of the value of the milk, because so much butterfat was lost in skimming the cream from crocks and pans and careless methods of making cheese left large quantities of fat in the whey.

The Babcock test gave creamerymen, cheese makers, and other dairy processors a more equitable basis for buying milk and cream and gave farmers a better way to measure the real value of their cows. This led to official testing of cows by the various breed associations and later to the Dairy Herd Improvement Association program, in which more than a thousand groups of dairy farmers all over the United States keep production records on more than a half million cows. Because of the check afforded by the Babcock test, housewives also can be assured of the legal amount of butterfat in every bottle of milk or cream.

Part of our tradition also is to evaluate science as science, to understand that a basic discovery has an importance as a foundation, if not as a superstructure. Among the early workers in plant sciences who made such fundamental discoveries was Merton B. Waite.

As a student at the University of Illinois, he came under the influence of T. J. Burrill, one of the great plant pathologists of his day and the first to demonstrate that bacteria caused many plant diseases. Only a few years earlier Pasteur had announced his discovery of bacterial diseases of man and animals. Young Waite was greatly impressed and decided to make his career the study of plant diseases.

He joined the Department in 1888. One of his first assignments was to make a study of pear blight, a disease that kills young branches of pear trees. In a few years the tree usually dies. At that time almost nothing was known about the disease except that it was caused by a bacterium. Waite observed insects feeding on pear blossoms and wondered if they might be responsible for spreading the disease from tree to tree. By carefully controlled experiments, he demonstrated his theory to be correct. He reported this work before the Association for the Advancement of Science in 1891, the year that the work of Theobald Smith and associates on tick fever was published. It would be interesting to know if either of these great men influenced the thinking of the other. At any rate, Waite's discovery helped to explain many of the plant diseases that are spread by insects and provided a foundation for other workers to build upon.

Like many another scientist who advances a new idea, Dr. Waite had many critics at first. One of these was a well-known doctor who owned an orchard on the Eastern Shore of Maryland. This doctor, according to a story that has been told in the Department for years, publicly challenged Waite to bring the pear blight bacteria to his orchard and infect his trees. Waite reluctantly accepted the challenge, and soon the doctor's pear trees began showing signs of blight, which eventually killed them.

Another far-reaching discovery by Waite was that most varieties of pears must be cross-pollinated with other varieties if they are to set a full crop. This finding was later found to apply to many other fruits, including apples, and has been a prominent factor in the choice of varieties for planting orchards.

Despite the brilliant work of Waite and many other plant pathologists, no fully satisfactory control has yet been found for pear blight. Some success has been achieved in breeding by crossing certain high-quality varieties with the Kieffer, which has much resistance to blight but is of poor quality. So far, only one new blight-resistant variety has been introduced by the Department. Its name, quite properly, is Waite.