RANKIN'S DUCK BOOK 



Figure 2. — Egg at End of 48 Hours. 



Figure 3 represents the egg at this stage, with its en- 

 larged air-cell. 



Figure 4 represents the egg as it appears at the end of 

 the fourth day. The circle surrounding and inclosing the 

 germ will have nearly doubled in size, and is of a still darker 

 hue ; indeed, the whole contents of the egg is perceptibly dark- 

 ened If the egg is broken carefully at this date a delicate 

 tracery of veins will be found to have enveloped the entire 

 yolk of the egg, all originating from the centre or heart of the 

 embryo; the pulsations of which (if the shell is removed) can 

 now be plainly seen with the naked eye. This net work of 

 veins cannot be plainly seen with a common lamp, but with 

 a powerful glass are very distinct. This latter is not at all 

 rnecessary in testing the egg. 



Figure 3. — Egg at End of 72 Hours. 

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