CHAPTER I. 



Introduction. 



THE POULTRY INDUSTRY— HEALTH AND DISEASE— THE OR- 

 GANS AND APPARATUS AND THEIR FUNCTIONS— COMMON 

 CAUSES OE DISEASE— HYGIENIC KEOUIREMENTS— DIS- 

 INFECTION— OBJECTS OF MEDICAL TREATMENT. 



THE POULTRY INDUSTRY. 



/mm^WE domesticated birds, which we group to- 

 / \ gether under the general term " poultry," 

 ^^i^ constitute a very important part of the " farm 

 animals " of the country. Their number and 

 value are enormous. There were in 1890 according to 

 the census 258,871,125 chickens or dung -hill fowls 

 and 26,738,315 other domesticated fowls in the United 

 States. This gives a total of 285,609,44(1 individual 

 fowls. The number at present in the country is un- 

 doubtedly much larger than in 1890. 



The annual earnings of American poultry amount to 

 an immense sum, and have been estimated all the way 

 from $200,000,000 to $350,000,000. The truth lies 

 somewhere between these extremes, but sufhcient data 

 has not been collected to enable any one to reach a 

 very accurate conclusion. It is certain, however, that 

 the poultry industry constitutes one of the most im- 

 portant branches of agriculture, and that it is well 



