METHODS OF HATCHING CHICKENS 283 



to be merely a protective device, but it is now known that 

 the developing chick draws upon the shell for a large part 

 of the lime necessary for its proper growth. The shell is 

 porous or permeable to gases ; this permits evaporation of 

 the water of the egg and also permits entrance of oxygen 

 necessary for the development of the embryo. 



How Long Should Laying Hens Be Kept. The pro- 

 ductive life of the hen is short compared with that of 

 domestic animals. It is apparently a natural characteristic 

 of the hen to lay more eggs in her first laying year than 

 in the second, and in each succeeding year a smaller num- 

 ber. The results of experiments by the writer at the Utah 

 Station showed average pen results from Leghorns in the 

 first year of 164 eggs, and in the second 126 per hen. In 

 exceptional individual cases more eggs were laid the second 

 year than the first. For instance, one hen laid 201 the 

 first year and 241 the second. Forty-one hens of different 

 breeds averaged 178 eggs the first year and 125 the second, 

 or 40% more the first than the second year. 



At the Oregon Station later results were secured as 

 follows : Fifty Barred Plymouth Rocks laid 160 eggs the first 

 year, and 105 the second year, and 50 White Leghorns and 

 crosses, 153 eggs the first year, and 130 the second year. 

 In these experiments the laying year began November 1. 

 Out of the 100 hens, 17 laid more eggs the second year than 

 the first. 



Other records showed, what might be expected, that 

 where the conditions for egg production were more favor- 

 able during the second year than the first, a better egg 

 yield was secured during the second year. Again, where 

 the period of maturity varied, or where the laying year 

 began in the spring, the second year records were better 

 than the first. The moulting period did not vary, making 

 the first laying year short 



