240 



POULTRY PRODl'CTION 



unusually cool nights, which are likely to produce crowding 

 if a little extra heat is not supplied. 



The thermometers used should be carefully tested at the 

 beginning of each season, if they are to be relied upon, just 

 as in the case of incul)ators. 



I-'i.;. 119 



.t«il.iiiiii hio.id, 1 Hum 1 in Inn „aoinii| 1 iistd i(iiintts\ 

 ol K nj^ 1^ \ jiuultui ]1 L\i ( niiii lit st iiion ) 



Effect of ChiUiiig.—k little chick compelled to remain in 

 the cold after he begins to feel chilly, soon becomes helpless. 

 This is apparently caused by the paralysis of the breathing 

 apparatus. The lungs are located on either side of the 

 median line of the back at the circumference of the body 

 cavity. Lobes of the lungs extend between the ribs and are 

 protected from the outside temperature only by a thin 

 membrane, the skin, and a coat of down. It is not surprising 

 that when the chick is chilled the lungs are quickly afl'ected, 

 breathing power restricted, and a general enfeeblement of the 

 powers of movement ensues. 



In natural brooding, the back and lungs are the best 

 protected portions of the body. When a chick becomes 



