A SELF-SUPPORTING HOME 



light of the tester, a solid spot about the 

 size of a pea, from which vinelike tendrils 

 extend, can distinctly be seen floating about 

 the centre of the egg. Dead germs, on the 

 contrary, usually adhere to one side. Only 

 experience enables one to test with certainty. 



You may ask, why risk taking any out? 

 The answer is, a dead germ causes the whole 

 egg to decompose. The shell being porous, the 

 harmful gases escape into the incubator and 

 poison the air on which the embryo chicks feed. 



To regulate the necessary ventilators is 

 even more difficult than to keep the heat even. 

 The guide is the air space at the top, or large 

 end, of the egg. If this expands too quickly, 

 there is too much ventilation; if too slowly, 

 there is not sufficient. The safest way to 

 study this point is to get one or two broody 

 hens, set them at the same time as the incu- 

 bator, then ventilate so as to have the incu- 

 bator eggs exactly equal to those under the 

 hens. 



After turning the eggs and replacing in 

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