LOUIS PASTEUR. 23 



tion of spontaneous generation. Believing, as he did, that 

 all fermentation was caused by micro-organisms, it was a fore- 

 gone conclusion that he would be an opponent to the view of 

 spontaneous generation. The studies upon fermentation which 

 he had been carrying on, and his accurate methods, trained 

 him especially well for this subject of spontaneous generation, and 

 the experiments which he instituted brought this question into the 

 condition of demonstration. The experiments of early scientists 

 were repeated by him with greater care ; many new experiments of 

 his own were devised ; the microscope was brought into requisi- 

 tion in new ways. A brilliant conclusion was reached, that by the 

 exercise of sufficient care all traces of life could be avoided, and 

 no spontaneous generation ever occurred. It is true that the con- 

 clusions of Pasteur were not at once everywhere accepted. In 

 England, particularly, objectors arose who advocated a belief in 

 spontaneous generation, and these objections were not silenced 

 until the EngHsh physicist, Tyndall, took up the experiments that 

 Pasteur had been making, and even more satisfactorily reached 

 the same conclusion. But Tyndall's results were only those that 

 Pasteur had reached before, and we recognise to-day that the only 

 basis of the objections that were made to Pasteur's conclusions 

 was the inaccuracy and lack of care with which his opponents 

 performed their experiments. With brilliant rhetoric and loose 

 experimenting, spontaneous generation was still advocated, but the 

 disproof was given by Pasteur in spite of the fact that opposition 

 still arose after the disproof had been reached. 



But now Pasteur's attention was to be turned again, and in a 

 direction that again changed his whole life and has revolutionised 

 modern medicine. One of the great industries of France is that 

 of the silkworm raising. About 1850 there appeared upon the 

 silkworm farms a disease of the silkworm known as pebrine. This 

 disease spread rapidly from farm to farm, greatly reduced the 

 productions of the silkworm farms, and actually threatened the 

 entire destruction of the silkworm industry. From 57,000,000 

 pounds per year, in thirteen years this industry had fallen to 

 8,000,000 pounds, all because of the great devastation produced 

 by this disease. Many had been the attempts made to cure it 

 and many the attempts made to discover its cause. Men with a 



