CHAPTER I. 



Introduction. 



The poultry industry— health and disease — the or- 

 gans AND APPARATUS AND THEIR FUNCTIONS — COMMON 

 CAUSES OF DISEASE — HYGIENIC REQUIREMENTS — DIS- 

 INFECTION — OBJECTS OF MEDICAL TREATMENT. 



THE POULTRY INDUSTRY. 



/^■■^HE domesticated birds, which we group to- 

 / \ gether under the general term "poultry," 

 ^^■v 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 285,609,440 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 sufficient 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 



