484 BOARD OF AGRICULTUKE. 



CHICKEN CHOLERA. 



The cliickeiis were dyiug of cholera. He discovered the germs of the 

 disease iu their blood. Could he cure it? One thing known to all of us 

 had a suggestion in it for him. When a disease like measles breaks out 

 in a community the first to have it have it severely; those Avho contract it 

 from them less severely, until finally the disease runs out all together. 

 Could he not attenuate the virus of chicken cholera? He made a pure 

 culture, exposed it to light and air and from time to time inoculated 

 chickens with it; he found that they had the disease less and less severely 

 until finally all of them recovered, and were found by inoculation to be 

 proof against the virulent form of the disease. Cause and cure had again 

 been found. 



A strange scourge fell upon Pharaoh's cattle. It fell as well upon all 

 the cattle of all the Pharaohs from the time of Moses to the time of 

 Pasteur. This was the next disease Pasteur studied. The bacillus an- 

 thracis that causes this disease is one of the largest of the bacilli. Sheep 

 and goats have the disease as well as cattle. There are three ways by 

 which contagious diseases are contracted— through the air we breath, 

 through our food and drink, and by the introduction of the germs into 

 the blood through the skin. Anthrax attacks men sometimes. It is called 

 in England Woolsorter's disease. The men who sort the wool get their 

 fingei's pricked with the burs and the bacilli get into the blood this way. 



Pasteur found the bacilli in the blood of an ox and made a pure cul- 

 ture. He tried keeping it and inoculating a sheep every day; but instead 

 of losing he found that it gained in virulence; the sheep became sicker 

 and died quicker. Pasteur did not know why. We now know that under 

 these circumstances the bacilli form spores; these are more virulent than 

 the bacillus itself. The obstacle is the spur to genius. Pasteur inoculated 

 several different kinds of animals. In this way he found out that chick- 

 ens are immune. Inoculate an ox that weighs 2,000 pounds, and it sickens 

 and dies; a chick of a few ounces, and it does not take the disease. Why? 

 Pasteur concluded that it might be because a hen is hotter than an ox. He 

 inoculated a hen and put her on ice and cooled her down to the tempera- 

 ture of an ox, and she took the fever and died. He took another and 

 gave her anthrax in the same way, and when her pulse rose and her 

 mind began to wander he put her in an incubator and heated her up to 

 the temperature of a hen, and she soon took on a benevolent expression, 

 got up, shook out her wings and would have crowed if she had been the 

 other sex. 



He now tried his pure cultures again, heated in an oven at 43 degrees 

 centigrade, and from day to day they lost their virulence, until at last the 

 sheep recovered and were immune against the virulent form of the dis- 

 ease. 



