SECTIOX XV 

 THE EGG 



COMPOSITION 



An average-sized hen egg weighs about two ounces, of 

 wliiich eleven per cent is shell, thirty-two per cent yolk, and 

 fifty-seven per cent white. The principal chemical constitu- 

 ents 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. 



Composition of the Egg Shell 



Gadow gives the composition of the egg shell as follows: 



Per Cent. 



Calcium carbonate 91.44 



Magnesium carbonate 2.03 



Calcium phosphate 70 



Organic phosphate 4,92 



Water 73 



Loss (or traces of other salts) 18 



Total 100.00 



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 iuffe.ra or Heferal-is papillosa and 

 other round worms, normally inhabiting the intestines, mav 

 find their way up the egg canal and be incorporated with the 

 egg as it is formed. By referring to Fig. 2, 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, devoted much 

 time to the investigation of the bacterial flora of eggs. It is 



