SECTION XV 



The Egg 



Composition 



An average-sized hen egg weighs about two 

 ounces, of which eleven per cent is shell, thirty-two 

 per cent yolk, and fifty-seven per cent white. The 

 principal chemical constituents of the egg are as 

 follows: Ash (mineral matter) nine per cent; fat 

 (hydrocarbon) nine and three-tenths per cent; 

 proteids (nitrogenous matter) eleven and nine- 

 tenths per cent; and water, sixty-five and five- 

 tenths per cent. 



Animal Parasites in Eggs 



Reports have been made that worms have been 

 found in eggs. The author has not had the good 

 fortune to examine any of these worms for the 

 purpose of classification, but it is probable that 

 the Ascaris inflexa or Heterakis papillosa and 

 other round worms, normally inhabiting the in- 

 testines, may find their way up the egg canal and 

 be incorporated with the egg as it is formed. By 

 referring to Plate I, it will be seen that a live 

 worm, possessing power of movement as these 

 worms do, passing into the cloaca (16) from the 

 rectum (15) can pass up the egg canal (23) and 

 thus be incorporated in the albumen of the egg, as 

 it is formed around the yolk. These conditions 

 are rare. 



Bacteria of Eggs 



Several investigators have, of recent years, de- 

 voted much time to the investigation of the bac- 



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