4 MASS. EXPERIMENT STATION BULLETIN 384 



Table 1. — Percentage of Chicks Emerging in Different Periods, by 

 Hatches, with Summary of Time of Emergence of All Chicks 



Mean Length of the Incubation Period in the Normal Hatching Season 



As previously indicated, the chicks were hatched in March and April, and 

 this may be considered the normal hatching season for this locality. All of the 

 hatches during the three-year period have been thrown together in the "Sum- 

 mary" in table 1 to get a general picture of the proportions of chicks emerging 

 during each of the seven 8-hour periods under the uniform conditions of m- 

 cubation used. 



About 42 percent of the chicks emerged during the last third of the 21st day 

 of incubation. At the end of the 21st day only 66.26 percent of the chicks had 

 emerged. The remaining one-third hatched during the 22d day of incubation. 

 Precautions were taken to have the incubator heated to about 100° F. for several 

 hours before receiving the eggs, and the temperature was maintained within a 

 half degree of the manufacturer's recommendations. The data in general indicate 

 that there was a wide fluctuation in the length of the incubation period, which 

 may or may not be a normal condition. 



Table 2. — Percentage of M.\les from 

 Different Emergent Periods 



