Incubation. — Part II 1395 



over a longer period as the embryo grows. In warm weather thirty to 

 sixty minutes may be needed to air the eggs properly during the latter 

 stages of incubation. On very sultry days extra cooling is beneficial; 

 less is desirable on cool days. In cold weather only a comparatively 

 short time will be required to cool the eggs sufficiently. Cooling may be 

 done after either the morning or the night turning, or at both times. If 

 the eggs are cooled twice daily, only half as long a period each time should 

 be required. 



Eggs may be cooled on a table, or perhaps on the incubator. Some 

 authorities advise cooling in the machine by dropping the door. If the 

 latter method is used, it is not generally advisable to cool the eggs so long 

 a time as in the former cases. While the doors remain open the heat is 

 constantly escaping, and the incubator becomes cooled as well as the eggs. 

 A longer time is then required to bring the egg chamber back to the proper 

 temperature than when the eggs are cooled outside and the incubator 

 kept closed. If the machine contains a moisture pan the door should not 

 be left open in cold weather. CooHng should be discontinued on the 

 nineteenth day. 



A great many accidents may be avoided if the operator forms the habit 

 of looking at the incubators before leaving the room, making sure that the 

 doors are closed and that everything is in place. 



TESTING 



Probably the most important of the several reasons for testing eggs 

 during incubation is to learn the percentage of fertility and the strength 

 of the germs. When these conditions are known to be unsatisfactory, it 

 may be possible to make such changes in the mating or in the environment 

 as will add to the fertility and strengthen the germs, thereby increasing the 

 percentage of eggs that will hatch and also improving the quality of the 

 chickens. When three or four incubators are started at the same time, the 

 eggs left in one machine may be divided among the others, thus saving oil 

 and lessening the labor. Removing the dead germs helps to prevent bad 

 odors that are sure to accumulate when eggs are being incubated. Odors 

 from duck eggs are more noticeable than from hen eggs. If in an incu- 

 bator, it is the more necessary that the bad eggs be removed. 



Carefully tested infertile incubator eggs, if put on the market promptly, 

 may be sold for a certain percentage of their original value. Incubator 

 eggs offered for sale should, of course, always be so labeled. In large 

 cities they are used in bakeries and for family cooking. There is no reason 

 why such eggs should not be used. They are, without doubt, as good as 

 or better than many of the so-called fresh eggs on the market. If white 

 eggs are being incubated and those that are infertile are to be sold for 



