372 



Agricultural Gazette of N.S.W . 



[May 3, 1920. 



Embryonic development at fourteen days. Nearly 

 all opaque. 



of this will be in proportion 

 to the number of infertiles left 

 in the machines, on account of 

 these eggs losing heat more 

 rapidly during turning and 

 cooling operations, and taking 

 much longer to regain any- 

 thing approaching the nor- 

 mal heat required after being 

 returned to the incubator. 



result that inpubator or hen 

 space is crowded throughout 

 the hatch. Not only so, but 

 in regard to incubators the 

 fact of a number of infertile 

 eggs being left in the machine 

 is more or less prejudicial to 

 the best results being obtained 

 from the fertilised ones, owing 

 to the fact that the infertile 

 eggs lack the animal heat that 

 is present in those eggs in 

 which embryonic development 

 is progressing. The ill effects 



Skilled operators can test 

 their eggs at from four to five 

 days with a good tester (par- 

 ticularly in the case of white- 

 shelled ones), but the novice 



Egg showing a broken yolk. This will not produce a 



living chicken even though some embryonic 



development may have taken place 



Embryonic development as seen at nineteen days, quite 

 opaque except for the air space marked 1 to 19 days. 



will do well to leave his testing 

 until the seventh day, but not 

 later, because at that time it 

 is much easier to test than 

 cither before or after. 



In order to assist the novice 

 in the testing of eggs under 

 incubation, illustrations have 

 been prepared of eggs both 

 fresh and in different stages of 

 development, as they are seen 

 in the ordinary egg-tester be- 

 fore a strong light. In a 

 medium or poor light the em- 

 bryo is seen only as a daik or 

 opaque substance occupying 

 portion of the space of the 

 egg, the remainder being clear 

 in the early stages. 



