ANATOMY OF THE EGG. 75 



culiar and delicate membrane ; the outer 

 layer is the most fluid and transparent. It 

 is chiefly composed of albumen, with a small 

 portion of sulphur. The presence of sul- 

 phur is indicated by the tarnish which it 

 gives to silver spoons. The yolk occupies 

 the centre of the egg, and is enveloped also 

 in its peculiar membrane, called the yolk- 

 bag. Besides albumen, the yolk contains 

 oil and phosphorus. This oil was formerly 

 much sought after, and employed by the 

 chemists of Europe for what they termed 

 killing mercury. It is obtained by boiling 

 the yolks, and then submitting them to pres- 

 sure ; in this way about five ounces of oil 

 are obtained from fifty eggs. From each 

 end of the yolk proceeds a white, knotty 

 body, terminating in the glaire by white, floc- 

 culen extremities ; these are termed chala- 

 zae, or cords. A round, milk-white spot, 

 called the treddle, and surrounded with con- 

 centric circles, termed in the books halones, 

 is only observed in such eggs as have been 

 impregnated. 



The shape and size of a lien's egg are too 



