262 



POULTRY PRODUCTION 



water drank by fowls is gotten rid of by means of the breath- 

 ing apparatus than is the case with other farm animals. 



The elaborateness of the apparatus itself would also suggest 

 this probability. Besides a well-developed pair of lungs, 

 there are connected with them four pairs of air sacs of 

 considerable proportions placed on either side of the body, 

 and ranging in position from the neck to the abdomen, with a 



Fig. 138 



A farm poultry-house: no light, no ventilation. (Courtesy of Purdue 

 Experiment Station.) 



single median sac located in the cavity of the thorax. 

 Besides opening into the lungs, these sacs communicate 

 directly with the cavities of most of the bones of the body, 

 with the exception of those of the forearm and hand of the 

 wing and those belo.w the hock-joint of the leg. 



This elaborate system for gathering moisture from every 

 part of the body trunk is working at a distinct disadvantage 

 when the air which must be depended upon to take up the 

 moisture vapor is already laden with it. 



