96 OUR DOMESTIC BIRDS 



on sitting hens, it is a good idea, even when the hen can dust 

 herself, to apply an insect powder to her and to the nest two 

 or three times during the period of incubation. 



The eggs may be tested at the end of the seventh day by using 

 a light, as described on page 21. While fertility can be deter- 

 mined earlier, waiting until the seventh day enables one to tell 

 more surely whether fertility is strong or weak, and to discard 

 weak germs as well as infertile eggs. An infertile egg is clear, 

 that is, shows no signs of development or decay, at every period 

 of incubation. The eggs that rot are fertile eggs in which the 

 germs have died. A rotten egg is distinguished from a fertile 

 egg through the tester by the movement of the line between the 

 transparent air space at the large end of the egg and the dark con- 

 tents, this movement showing that the contents are in a fluid state. 

 The eggs which are the most opaque and have the air space most 

 distinctly marked are those which have the strongest germs. 

 Eggs that are conspicuously light-colored (as they appear before 

 the light ) when compared with these may as well be discarded. 

 If many eggs are discarded, those that remain may be given to a 

 part of the hens, and the rest of the hens reset. 



Attention at hatching time. The eggs of medium-sized fowls 

 usually hatch in from twenty to twenty-one days. The eggs of 

 small fowls take about a day less, and those of large fowls about 

 a day more. Hens' eggs have been known to hatch as early 

 as the seventeenth day and as late as the twenty-fourth, but 

 as a rule chickens that come before the nineteenth day or after 

 the twenty-second are weakly. Hens sometimes trample the 

 chickens in the nests or crush the eggs after they are picked, 

 so that the chicken cannot turn to break the shell in the regular 

 manner. Sometimes this is due to the nervousness or to the 

 clumsiness of the hen, but oftener it is caused by the nest being 

 too much dished (that is, hollowed so much that the eggs tend to 

 roll toward the center) or by lice disturbing her. The chickens 

 may be saved either by removing them to other broody hens or by 



