METHODS OF HATCHING CHICKENS 319 



the hen for successful hatching, but experiments at Utah 

 in supplying artificially a large quantity of this gas rather 

 injured than improved the hatching of the incubator. This 

 has been corroborated by experiments at Storrs. It has 

 not been proved that an artificial supply of carbon dioxide 

 will help matters. 



Oil on Egg Shells. Investigation at the Oregon Station 

 (Bulletin 100) has revealed another point in which it is 

 difficult to imitate nature. It was discovered that the shells 

 of eggs under the sitting hens contain a considerable 

 quantity of oil. A fresh unincubated egg contained a small 

 quantity of oil, but eggs that had been under the sitting hen 

 for two weeks contained six times more oil, while the eggs 

 that had been in the incubator contained practically the 

 same amount as fresh eggs, proving that oil was deposited on 

 the eggs by the hen. What the function of this oil is in in- 

 cubation, is not yet known. 



Whatever may be the practical result, it is thus seen that 

 the sitting hen is slowly giving up some of her secrets to 

 scientific research. 



