Men Who Went Before

by ERNEST G. MOORE

THOSE who work in farm science have a noble tradition to live up to. It is the tradition of Marion Dorset, Theobald Smith, Henry Ayers, L. O. Howard, Erwin Smith, Harvey Wiley, W. O. Atwater. It is a tradition of vision and hard sense, of service and the eternal quest. It is a tradition of inquiry. Marion Dorset was an inquiring man and hard-headed one. He came to work for the Department of Agriculture in 1894, a time when hog cholera was causing large losses. In some of the bad years losses amounted to more than 65 million dollars. Associates in the Bureau of Animal Industry assured the 23-year-old lad from Tennessee that they had already found the cause of the disease to be a bacterium. Dorset's job, they explained, was to find a preventive or cure. His superiors had even made a start on this—they had prepared a serum from the bacteria that seemed to be causing the trouble.

In the summer of 1897 hog cholera flared up in Iowa, so Dorset was sent posthaste, armed with the new serum. He spent a good part of the summer injecting this serum into sick hogs and well hogs, but they still died of cholera. He returned to Washington and began all over. After his experience in Iowa both Dorset and his immediate chief, E. A. de Schweinitz, questioned the widespread belief that bacteria were responsible for the cholera. This took courage, because it amounted to defying their own superiors and nearly all scientific thought at the time. Dr. de Schweinitz died before Dorset discovered the true cause of cholera.

It was 6 years before there was another disastrous outbreak of the disease. The interval gave Dorset time to work on other things, to get his degree in medicine by attending night classes, and to challenge, with growing success, the bacteria theory about hog cholera. He demonstrated that the causative agent was not a bacterium at all, but an ultramicro scopic virus. He also proved that hogs that recovered from the disease were immune for life.

Back to Iowa he went in the summer of 1903, but this time he was armed with more potent weapons. With the help of C. N. McBryde and W. B. Niles, he went to work again. They found that blood from immune hogs gave temporary immunity to other hogs, but it lasted only a few weeks. Then Dorset hit upon the idea of using two injections. The first was a serum from the blood of a hog that had lived through an attack of cholera and further demonstrated its immunity by surviving a large shot of virus, the blood from an infected hog. The other injection was virus. With slight modification, this treatment is still in use.

Marion Dorset died in 1935. Citizens of his native Tennessee have placed a plaque in his honor in the Agricultural Hall of Fame in Nashville.

Like many other Department scientists, Dr. Dorset patented his discovery and dedicated it to the public, making it possible for anyone to use his method for making serum without paying royalty.

Another part of the tradition of those who work in farm science is that costs must be counted closely, but not the credit or the value, because one can measure only a part of the value of agricultural research. You can often make a pretty fair estimate of the money it has saved or added to our national income; you can even make a fair guess as to the value of agricultural research to the health of the people, but there is no yardstick for measuring its ultimate value. Those evaluations come only with the passage of years. When Theobald Smith found that the way to control tick fever of cattle was to control the ticks, no one knew that his brilliant research would pave the way for control of malaria, yellow fever, and many other scourges of the Tropics. These developments came several years later and were the work of other men.

Around 1890 tick fever of cattle was causing widespread losses, especially in the South. Southern cattle were often driven to northern markets, and they usually left a trail of fever along the way. Northern cattle, taken to the South for breeding, usually contracted the disease and died. Many southern cattlemen believed that ticks were somehow responsible for the disease, because cattle that died from it always had ticks on them. At first, there was no scientific evidence to support the belief, but the scientists eventually proved that the cattlemen were right.

Theobald Smith began work on tick fever in 1888. Later he was joined by Dr. F. L. Kilborne and Dr. Cooper Curtice. Smith and Kilborne discovered the cause of the disease to be a protozoan parasite, found in the blood of infected animals. In the summer of 1890 they definitely established the fact that the disease was spread from animal to animal by the cattle tick. That was the first demonstration that a disease-producing micro-organism can be transmitted by an insect carrier from one animal to another. ( Working independently, as far as I can learn, Dr. M. B. Waite made the same fundamental discovery in relation to insect transmission of plant diseases.) The obvious cure for the disease was to get rid of cattle ticks, and this was done through a long-time eradication program conducted jointly by the Department and the States.

Getting rid of cattle ticks and tick fever has meant untold millions of dollars to cattle growers of the South; this research cost $65,000, for salaries and expenses, and the Department sets the value of the discovery at about 40 million dollars a year. But you cannot fully measure its value: The implications of the research that paved the way for the discovery go far beyond the borders of our country and the monetary value of livestock. Other research men were quick to see the possibilities for conquest of human diseases. In a few years the mosquito was recognized as the carrier of yellow fever, and the work of another Department scientist, Dr. L. O. Howard, furnished basic information for campaigns to eradicate mosquitoes. With this malady under control, it was possible for the United States to build the Panama Canal. French engineers had failed because they were unable to control yellow fever.