19 



TESTING EGGS. 



This is a very necessary proceed- 

 ing, in order to remove any infertile 

 or dead eggs. As there is a difference 

 of about 3 between a dead and a live 

 egg, there is a danger of the ther- 

 mometer bulb resting on a bad one, 

 and the live ones becoming over- 

 heated. The best time to make the 

 first test is on the fifth or sixth night. 

 Hold the egg between the forefinger 

 and thumb, or in a tester that is 

 usually supplied with incubators; look 

 through the egg at a strong light. If 

 the egg is fertile it will appear like that 

 shown in the margin, and slightly red 

 in colour; if addled, a black spot will 

 be visible; if infertile, it will be quite 

 clear. The latter may be used for culi- 

 nary purposes, or boiled for chickens 

 already hatched. A second testing 

 about the twelfth day is advisable. 



An ordinary small lamp or a candle may be utilised as an egg- 

 tester by fixing a piece of cardboard, in the centre of which an opening 

 the size and shape of an egg has been cut, in front of the flame. The 

 rays of the light are thus focussed through the egg. Reliable results 

 are obtained in this way. 



DEVELOPMENT OP THE AIR-CELL. 



FERTILE EGO. 



(TEN EGO. 



DUCK EGG. 



A capital plan is also to note the development of the air-cell; it 

 becomes larger as the chick develops. The diagrams show the development 

 that should take place at the respective number of days. 



