THE PROGRESS OF ZOOLOGY 477 



able to combine the two ; such a one was Louis Pasteur (Fig. 



325)- 



Pasteur was born at Dole in eastern France in 1822. He 

 was particularly interested in chemistry, but is most famous 

 because of his contributions to biology. His first investiga- 

 tions were concerned with the phenomena of fermentation and 

 decay. By proving that only living microorganisms (yeast 

 and bacteria) can cause fermentation, he was able to suggest a 

 method of preventing this process by heating substances to 

 a temperature high enough to kill these germs. This method of 

 killing germs is now known as pasteurization and has saved 

 billions of dollars and thousands of lives since milk and other 

 liquids can be preserved in this way. 



Pasteur's attention was next called to a silk-worm disease 

 which was killing off the silkworms in France and Italy and thus 

 destroying a very important industry. By long investigations 

 he proved that certain germs in the eggs, larvae, pupae, and adults 

 were responsible for the trouble, and by suggesting a scientific 

 method of control succeeded in eradicating the disease. 



The Pasteur Institutes that now exist in many cities through- 

 out the civilized world have for their object the treatment of 

 hydrophobia. This disease was found by Pasteur to attack the 

 nervous system of victims bitten by mad dogs and other animals. 

 The treatment was also discovered by him. It consists in first 

 burning (cauterizing) the wound with strong nitric acid and 

 then injecting into the patient a specially prepared solution 

 (virus) every day for three weeks. Of over 20,000 cases treated 

 in Paris less than one per cent have died. 



Pasteur's discoveries were extremely important from the 

 standpoint of both pure science and applied science. They 

 also led more or less directly to discoveries made by his con- 

 temporaries and followers. Among these are Lister's treatment 

 of wounds by means of antiseptics and Roux's and Behring's 

 antitoxin for diphtheria. 



Zoological Progress of To-day. There are many zoologists 



