These studies in minute life and in fermentation led him almost naturally to the study of disease. Two centuries before, Robert Boyle, of whom his notorious descendant the great bullster, Sir Boyle Roche, had said that he was the father of chemistry and the brother of the Earl of Cork, made use of an expression wonderfully prophetic in its accurate penetration of the future. "He that thoroughly understands the nature of ferments and fermentations," said Boyle, "shall probably be much better able than he that ignores them to give a fair account of divers phenomena of certain diseases (as well fevers as others) which will perhaps be never properly understood without an insight into the doctrine of fermentations." The marvel is that the very first man who understood the nature of fermentation proved to be the one destined to unlock the mystery of contagious disease and its origin. Pasteur's first investigations in the field of disease concerned a mysterious malady that affected the silkworm and was ruining the silk industry of France. This disease was first noted seriously about 1850. When a colony of silkworms had been attacked it was useless to try to do anything with them. The only resource for the silk farmers was to get the eggs of an unaffected race of worms from some distant country. These became infected after several generations, {307} and untainted eggs had to be brought from a distance once more. Soon the silkworm plague invaded most of the silk-growing countries of Europe. In 1864, only the races of silkworms in China and Japan were surely not infected. Great suffering had been entailed on many departments of France by the failure of the silk industry. The most careful investigation failed to reveal any method of combating the disease. Acute observers had been at work and some very suggestive observations on the affected worms had been made, but the solution of the problem of the prevention of the disease seemed as far off as ever. In 1863 the French minister of agriculture formally agreed to pay 500,000 francs (about $100,000) to an Italian investigator who claimed to have found a remedy for the disease, if his remedy proved efficient. The offer was to no purpose. In 1865 the weight of cocoons of silk had fallen to 4,000,000 kilos. It had formerly been nearly 30,000,000 kilos. This involved a yearly loss of 100,000,000 francs (about $20,000,000).